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Genital lesions in experimental Trypanosoma congolense infection in heifers
BnimclIRqroducfion Sri~ncr. 26 (1991) l-l Elsevier Science Publishers B.V.. Amsterdam
1
1
Genital ksions in experimental Trypzn~soma congdense infection in heifers
ABSTRACT Ogwu. D. and Njoku, C.O., 1991. Genital lesions in experimental TrVpanosoma congolenre infection in heifers. Anim. Reprod. Sci.. 26: I-I I. A group of normocyclic heifers experimenfally infected with Tryponosomc congoktw (strain 2295) became anoestrooswithin 50 daysof infection. This foilowed a dramatic lossof body condition which character&d the onset of parasitaemia, Dyrexia and anaemia. Grossly, the ovaries of the infected heifers were atrophic and weighed signifi anlly less than those of the controls (PiO.05 1. Histopathological sections revealed muhiple follic s lar cystic degeneration and a complete absence of corpora lutea, Fnthe uterus, there was massive endometrial mononuclear cell inliltration. glandular atrophy, pcriglandul8r cell idltra~ion, myometrial atrophy and tibroplasia. There was cellular inliltration into Ihe cervix which had non-secretory desquamaied mucosa. The vaginal lesions were character&d by mononuclear cell intilcration and necrosis. The severity of the lesions was directly related to the duration of infection.
INTRODUCI-ION
Tine three principal pathogenic trypanosomes of ruminants (Tr~panosoma vivux, Trypanosomacongoienseand ivpanosoma brucei) have been ciassified into haematic and tissue groups (Losos and Ikede, 1972; Ranks, 1978). While the 7’. bnrcei subgroup local&s in tissues, particularly the connective tissue stroma, causing extensive damage (Griffin, 1978; L.OSOS, 1978), T. viYUX and T. cungolense are known to lodge preferentially in capillaries, where they attach to the vascular endothelium and seldom leave the bloodstream (Bungener and Muller, 1976; Banks, I973 ) . These trypanosomes are, therefore, not known to cause extensive tissue damage. There is, however, enough evidence to show that these so-called haematic trypanosomes do cause tissue damage in trypanosusceptible animais (Kaaya and Oduor-CRelo, 1980; Olubayo and Mugew, 1987; Sekoni, 1987; Mutayoba et al., 1988).
03784320/91/$03.50
0 1991 Elsevier Science Publishers B.V. All rights reserved.
D. OGW” AND C.O. NJOKU
2
Severe degenerative changes have been observed in the reproductive organs of animals (Ikede and Loses, 1972, 1975; Isoun et al., 1975; Ikede. 1979; Anosa and Isoun, 1980; Kaaya and Oduor-Okelo, 1980; Sekoni, 1987; Mutayoba et al., 1988). Most ofthese observations have been made with the brucei subgroup and in most cases in male animals. In female animals, irregular oestrus, infertility, anoestrus, abortion and premature deliveries have been observed (Murray et al,, 1981;Ogwu, 1983;Ogwu et al., 1984, 1986; Luckinset al., 1986; Mutayoba et al., 1988). Despite these clinical observations, there are only a few reports oftrypanosome-induced genital lesions in females. Cystic degeneration of the ovaries appears to be the only consistent finding in the genitalia of animals infected with the haematic trypanosomes (Vohradsky, 197 1;Isoun and Anosa, 1974; Mutayoba et al., 1988). This study was designed to provide the pathological basis for some of the observed reproductive dysfunctions in cows infected with T. congolense. MATERIALS
AND METHODS
Six normally cycling Bunaji (80s indicrts) heifers were acquired from the Ahmadu Bello University Farm. On arrival at the Faculty of Veterinary Medicine, all the heifers were screened for brucellosis and leptospirosis. Baseline haematological data were obtained and their blood samples were examined for the presence of haemoparasites. The heifers were allowed a 2 month acclimatisation period, during which their oestrous activities were recorded. All the heifers were housed at the Faculty of Veterinary Medicine Research pens and fed grass hay supplemented with cotton seed cake and wheat offals before and throughout the experimental period. They were also given mineralised salt lick and water ad libitum. Four of the heifers were inoculated with approximately 1.5x lo6 T. congoIUW (strain 2295) via jugular venepuncture. The trypanosomes. which have been studied extensively (Sekoni, 1987), were obtained from the Department of Veterinary Parasitology and Entomology of Ahmadu Beilo University, Zaria. The parasites were stored in stabilates, preserved in 5% dimethyl sulphoxide and stored in liquid Atlogea. Prior to use, the stabi!atc v~srps inoculated into a sheep which subsequently developed clinical trypanosomiasis. Blood from the sheep was then used for the experimental infection. The two remaining heifers served as the uninfected controls. Following inoculation, blood samples were collected daily until parasitaemia was established and then twice weekly thereafter. In addition to determining parasitaemia, the blood samples were used to monitor anaemia and other haematological parameters. Body temperatures were taken between 8
and 9 a.m., before taking the blood samples, Changes in body condition were noted, while the reproductive activities of the heifers were monitored by once weekly rectal palpation of the genitalia, as recommended
by Zemjanis ( 1970).
GENITAL LESlONSlN TR,‘b?I.VOSO.I4 ~~O,\‘GOLFWEINFECTED
HEIFERS
The genitalia of the heifers killed when moribund, or at the end of the experimsnt as the controls, were harvested. The ovaries were weighed, then trimmed and processed for histopathofogical studies. AH the tissues were fixed in Bouin’s solution and paraffin-embedded sections were cut at 5 m on a sliding microtome and stained with Ehrlich’s haematoxylin and eosin (I-f & E ). Several histopathological sections were prepared for each heifer and studied in detail with a standard tight microscope. RESULTS
Ciinical obse.rvations The trypanosome had a pre-patent period of 5 days. The highest parasitaemia was recorded between the 10th and 20th day post-infection. Thereafter, parasitaemia fluctuated until the end of the experiment. All the infected heifers developed a severe form of trypanosomiasis, characterised by rapid weight loss. lethargy, weakness, lacrimation, roughened coat, pale mucous membranes, superficial lymphadenopathy and fluctustizg pyrexia, culminating in the heifers becoming moribund and their subsequent slaughter on Days 50, 71 and 113for the first, second, third and fuutih infected heifers, respectively. By Day 40. all the infected heifers had become anoestnts. A fluctuating rectal temperature of up to 40.2”C was recorded in all the infected heifers, while the control heifers had a normal rectal temperature (38.&38.6”C). This difference was significant (P
Gross puthologicalJindings in the genitalia The ovaries of the infected heifers were small and atrophic, devoid of any functional structures and had a mean weight of 8.04 2 2.2 g. In contrast, the ovaries of the control heifers had a mean weight of I 1.6 2 0.07 g (Table 1). In addition, the ovaries of the control heifers contained functional structures (follicles and corpora iutea: developing, developed or regressing). Similarly, the tubular genitalia of the infected heifers were atrophic and infantile in comparison to those of the control heifers. The uterine lumina were exaggerated and the walls had a rough conformation caused by the prominent vasculature and the atrophic myometrium.
D. OGWU AND C.0
4 TABLE
NIOKU
I
Heifer No.
Ovarian weigh1
Mt?aIl
5.9 7.2 a.6 8.9 9.8 9.5 6.6 6.8
7.05
11.5 12.4 11.0 Il.5
11.95
Mean weight of infected and conrrol + SD
Inficred L&l ovary Right ovary Left ovary Right cwuy Left ovary Kight ovary Left ovary Right ovary
399 102033 107 661
Conrrof 645
Left ovary Right ovary Left ovary Right ovary
649
SD. standard
8.04-c 2.2
8.75 9.65 6.1
11.61U.Oi
Il.25
deviation.
The infected heifer slaughtered on Day 50 had a relatively normal ovarian histology. There were, however, increased numbers of degenerating tertiary follicles and a complete absence of corpora lutea. In the infected heifers killed on Days 7 I and 113, the ovaries were characterisedby polycystic degeneration (Fig. I), multiple degeneration of tertiary follicles, the absence of developing, developed or regressing, corpora lutea and Graafian follicles, a decreased number of primordial and secondary follicles, and slight fibrosis of the cortex (Fig. 2). One striking feature of the ovaries of the infected heifers slaughtered on Day 113 was the proliferation of the rete ovarii. Severe inflammatory lesions were observed in the uterus of the infected heifers. Myzme?ris! and endometrial cellular in!Nra!ions, comprising mainly lymphocytes, macrophages and plasma cells, were observed. In addition, there were focal areas of cellular infiltration into the myometrium and periglandular areas (Fig. 3 ). As demonstrated in Fig. 4, immediately beneath the endometrial surface epithelium is a collection of stromal lymphocytes, macrophagesand plasma cells. There was also lymphoid proliferationin the endometrium of the infected heifers (Fig. 5). The two heifers slaughtered on Day I I3 showed, additionally, evidence of chronic endometritis characterised by distorted and atrophic endometrial glands (Fig. 6) and fibroplasia. Myometri~I atrophy, observed in all the infected heifers. was more severe
5
Fig. 1. Ovary ofan infectedheifer with cysticdegeneration (H&E; magnification, X 160).
Fig. 2. Ovary of an infected heifer. Note the paucity of primordial and secondary follicles. and slight fibrosis (H & E: mapi!ication. X 63).
in the three heifers slaughtered on Days 7 1 and 113. The muscular atrophy was accompanied by a prominent vascular proliferation and hypertrophy of the vascular wall (Fig. 7), culminating in some cases in endometrial vascular arteriosclerosis.
Fig. 3. IJkrus of an infectedheifer.Note the focalarea uf mononuclear cell infiltraticm in the endometrium(H & E; magnjtication,X 250).
Fig.4. U~crusof an infectedheifer.No& the diffusecellularintitrra~ionand glandularatrophy (l-l R:E: magnificnlion,x63).
UNITAL
LESli)NS IN TRYF!4hOSO>IfA CONGOLENSE INFECTED HElFERS
7
Fig. 5. Uterus of an infected heifer. Note the lymphoid hyperplasia in the endometriuimr(H& E: magnification. X 160).
Fig. 6. Uterus of an infected heifer showing glandularatrophy (H & E: magnification, X :160). In the cervix of the infected heifers there was cellular infiltration and a slight fibrosis. The mucosa was non-secretory and desquamated. The vaginal mucosa of the infected heifers was necrotic and sloughed There
D. OGWU AND C.O. NJOKU
Fig. 7. Uterus of an infected heiFer showing myometrirl atrophy, vascular hyperlrophy and fibroplasia (H %E: magnification, x 160).
were also areas ofcellular infiltration, again m&e up of mainly lymphocytes, macrophages and plasma cells (Figs 8 and 9 1.
GENITAL
LESIONS1N TAYP..N~SIM&ICONGDLENSE INFECTED HEIFERS
Fig. 9. Vagina of an infected heifer. Note the mononuclear cell infiltration tion, X 160).
(H&E; magnifica-
DISCUSSION
The clinical observations reported here are in agreement with those reported by Sekoni ( 1987) using the same strain of trypanosome. They are similar to our earlier observations with T. uivcucstrain Y58 (Ogwu et al., 1984). The mechanisms involved in the observed ovarian pathology require very careful study. In this investigation, the ovaries of the infected heifers were atrophic and devoid of functional structures, combined with multiple cystic degeneration of the follicles and first degree atresia of the Graalian follicles as describedby Rajakoski ( 1960). The pathogenesis of these ovarian lesions may not be unconnected with the hypothalamic-hypophyseal pathology observed in the infected heifers (D. Ogwu and C.O. Njoku, unpublished data, 1990 ) . While most of the lesions may be a direct effect of the endocrine dysfunction of the gonadotrophins, the direct effects of the trypanosome orgad nisms are yet to be explained. The cystic degeneration of the ovaries often reported in trypanosomal infections (Vohradsky, 1971; lsoun and Anosa, 1974; Mutayoba et al., 1988) are often thought to be due to a lack of preovulatory luteinising hormone surge (Luckins et al., 1986; Kutayoba et ai., 1988). However, the hypothalamic-hypophyseal pathology limiting the preovulatory surge should also have affected the follicular growth. Attempts should be made additionally to ascertain the effects of thyroid pathology on . k--=-n -*REPrwtir of the ova&r; this as h;-pt. 5,f roidrsm . :s ..“ll.. +n .Y ___I_ _,“.._ degeneration
in animals (Turner and Bagnara, 1976), and severe thyroid pathology has been described in trypanosomal infection (Mutayoba et al., 1988; D. Sgwu and C.Q. Njoku, unpublished data, 1990). Tbe observed atrophy of the tubular genitalia may be due to acyclic&y resulting from the ovarian pathology and the apparent lack or decrease of ovarian hormones. However, the more serious lesions of the tubular genitalia include the inflammatory changes, myometrial atrophy, and vascular and lymphoid hyperplasia. These are capable of causing infertility, even if the ovarian pathology were absent. Similarly, the observed cervicitis, when combined with vaginitis characterised by mucosal necrosis and sloughing, has grave reproductive consequence?. The significance or importance of the proliferation of the rete ovarii is not known, but may be associated with the mitogenic activities seen in try ranosomal infection (Esuruoso, 1976). The serious myometrial atrophy, vascular proliferation, hypertrophy and subsequent sclerosis, and the ability of these animals to restore their fertility following natural infection, require further scrutiny. Finally, attempts are being made to carry out the same investigation using trypanotolerant breeds like the N’dama which have been reported to have high residual fertility (Murray et al., 1981).
REFERENCES Anosa. V.O. and Isoun, T.T.. 1980. Further observation on the testicular patholqy in Trypo)IoSO?NR~‘JWX infecliou of sheep and goats. Res. Vet. .Sci,. 28: 60. Banks. K.L.. 1978. Binding of Tryp~nosoma cong&nse to the walls of small blood vessels. 1. Ptot~zcoj... 25: 241-2d5. Bungener. W. and Muller. G., 1976. Adherence phenomena tn D~punosomo cungoknse. Z. Tmpenmed. Pamsitol.. 27: 270-383. Eruruoso. GO., 1976. The dt ..ionstration jn vitro of the mitogenic effects of trypanosomal antigen on the spleen cells of normal, athymic. and cyclophosphamide-treated mice. Clin. Exp. Immunol., 23: 314-317. Griffin. L., 1978. African trypanosomiasis in sheep and goats: A review. Vet. Bull.. 48: 819825. tkedc. 5.0.. 1979. Geniial lesions in experimental chronic 7’r,vpunosoma brrtrel infection in rams. Rcs. Vet. Sci.. 26: 145-151. lkcde. B.0. and Loses. G.J., 1972. Pathology of the disease in sheep produced experimenially by Trri~~tivsnma I~rrrc~~.Vet. Pothol.. 9: 278-289. Ikede, B.O. and Loses. 6.1.. 1975. Pathogcnesis of infection in sheep. I. rlilriral cignc Path&. 85: 23-3i.
I51-I
I Cwp.
Trypmtososta bntcri
Isouu. T.T. and Anosa, V.O., t974. Lesions in the reproductive organs of sheep and goats infected with Tqvonossomu v&x 2. Tropnmcd. Pa&tol.. 25: 469-476. Isoun. T.T., Akpokodje. J.&r. and Anera, V.0.. 1975. Testicular changes in white Fuiani Zebu (BuiJi) cattle experimentally infected with Tr):txxrtoso8na vivrrr. A preliminary report. J. !‘%er. Vet. Med. Assoc., 4: lo?-IBE. Kenya. G.P. und LM-uor-Okelo. D.. 1980. The effects of T~.vpanosuma congolenw infection on the testis andepidldymjsofthe~ect. Bull. Anim. Heatth Fmd. Afr.. 28: 1-5.
GENITAL LESIONS IN TRYF!I.VOSO.W4 C‘O.wXJLE.VSE INFECTED HEIFERS
II
Loses, G.J., 1978. Infections caused by African trypanosomes. In: G.J. Loses and A. Chouinard (Editors). Pathogenicity of Trypanosomcs. IDRC-1329. Ottawa. Canada, pp. 183-318. Loses, G.J. and lkede. B.O.. 1972. Review of the pathology of diseases of domestic and Iaboratory animals caused by Tr~panosorna congofcnse, T. rirar, T. bntcei. T. rhodesienre and T. w~rhiense. Vet. Pathol., P(Suppt.): l-7 I. Luckins, A.G.. Uewelyn. C., Munro. C.D. and Murray, M.. 1986. Eifects of pathogenic trypanosomes on the mammalian repmductive system. IAEA-Q&292/34, pp. 351-363. Murray. M.,Clifford. D.J., Gertinby. G., Snow, W.F. and McEntyre. W.I.M., 1981. Susceptibility to A%can trypanosomiasis of N’dama and Zebu cattle in an area of Glossina ~norsirans srtbmorsil~~ns challenge. Vet. Rec., 09: 503-5 IO. Mutayoba, B.M., Gombe, S.. Kaaya. G.P. and Waindi. EN.. 1988. Efficr ofchronir experimental Ttyanosome ccmngoknseinfection on the o :aries. piruitary, thyroid and adrenal glands in female goats. Res. Ver. Sci., 44: 140-146. Ogwu, D., 1983. Effects of Trypunosomo virus infection on female reproduction in cattle. PhD Thesis. Ahmadu Be110 University, Zaria, Nigeria. Ogw, D., Njoku. CO., Osori, D.I.K.. Ezwkoli. C.D. and Kumi-Diaka, J.. 1984. Effects of experimental Trypano.roma riwx infection on fertility of heifen. Theriogenology, 22: 625633. Ogwu, D.. Njoku. C.O. and Osori, D.I.K., 1986. EXccts of experimental Tr~pnnosonta viwx infection on first. second and third trimesrcr pregnancy in heifers. Theriogcnology, 25: 383-
i
398. Olubayo,
viwx
R.O. and Mugera, GM.. 1987. The pathogenesis of haemorrhage in Trypanosoma infection. 11. Pathomorphological changes. Bull. Anim. Health Prod. Afr., 35: 286-
292. Rajakoski. E.. 1960. The ovarian follicular system in sexually mafure heifer5 with special referen$ seasonal. cyclicaland left-right vtiations. Copenhagen. Acla Endoerinol.. 34( Suppl. ): Sekoni. V:O., 1987. Effect of Tvmnosoma
V~V(U, Ttypanasoma
cojlgo!ense infections and sea-
son on reproduction in the bull. PhD Thesis, Ahmadu Belle University, Zaria, Nigeria. Turner, C.D. and Bagnara, J.T.. 1976. General Endocrinology. 6th Edn. Saunders, Philadelphia, 3p. 178-195. Vohradsky. F.. 197 I. Clinical signs, daily rate of infection. physical changes of the blood and pethomorphologieal changes in cattle artificiafly infected with rr~panasorna vivcu. Rev. Elev. Med. Vet. Pays. frop., 24: 25 i-263. Zemjanis, R., 1970. Diagnostic and Therapeutic Technics in Animal Reproduction. 2nd Edn. Williamsand Wilkins, Baltimore, MD, pp. I-79.
I
1
1
Genital ksions in experimental Trypzn~soma congdense infection in heifers
ABSTRACT Ogwu. D. and Njoku, C.O., 1991. Genital lesions in experimental TrVpanosoma congolenre infection in heifers. Anim. Reprod. Sci.. 26: I-I I. A group of normocyclic heifers experimenfally infected with Tryponosomc congoktw (strain 2295) became anoestrooswithin 50 daysof infection. This foilowed a dramatic lossof body condition which character&d the onset of parasitaemia, Dyrexia and anaemia. Grossly, the ovaries of the infected heifers were atrophic and weighed signifi anlly less than those of the controls (PiO.05 1. Histopathological sections revealed muhiple follic s lar cystic degeneration and a complete absence of corpora lutea, Fnthe uterus, there was massive endometrial mononuclear cell inliltration. glandular atrophy, pcriglandul8r cell idltra~ion, myometrial atrophy and tibroplasia. There was cellular inliltration into Ihe cervix which had non-secretory desquamaied mucosa. The vaginal lesions were character&d by mononuclear cell intilcration and necrosis. The severity of the lesions was directly related to the duration of infection.
INTRODUCI-ION
Tine three principal pathogenic trypanosomes of ruminants (Tr~panosoma vivux, Trypanosomacongoienseand ivpanosoma brucei) have been ciassified into haematic and tissue groups (Losos and Ikede, 1972; Ranks, 1978). While the 7’. bnrcei subgroup local&s in tissues, particularly the connective tissue stroma, causing extensive damage (Griffin, 1978; L.OSOS, 1978), T. viYUX and T. cungolense are known to lodge preferentially in capillaries, where they attach to the vascular endothelium and seldom leave the bloodstream (Bungener and Muller, 1976; Banks, I973 ) . These trypanosomes are, therefore, not known to cause extensive tissue damage. There is, however, enough evidence to show that these so-called haematic trypanosomes do cause tissue damage in trypanosusceptible animais (Kaaya and Oduor-CRelo, 1980; Olubayo and Mugew, 1987; Sekoni, 1987; Mutayoba et al., 1988).
03784320/91/$03.50
0 1991 Elsevier Science Publishers B.V. All rights reserved.
D. OGW” AND C.O. NJOKU
2
Severe degenerative changes have been observed in the reproductive organs of animals (Ikede and Loses, 1972, 1975; Isoun et al., 1975; Ikede. 1979; Anosa and Isoun, 1980; Kaaya and Oduor-Okelo, 1980; Sekoni, 1987; Mutayoba et al., 1988). Most ofthese observations have been made with the brucei subgroup and in most cases in male animals. In female animals, irregular oestrus, infertility, anoestrus, abortion and premature deliveries have been observed (Murray et al,, 1981;Ogwu, 1983;Ogwu et al., 1984, 1986; Luckinset al., 1986; Mutayoba et al., 1988). Despite these clinical observations, there are only a few reports oftrypanosome-induced genital lesions in females. Cystic degeneration of the ovaries appears to be the only consistent finding in the genitalia of animals infected with the haematic trypanosomes (Vohradsky, 197 1;Isoun and Anosa, 1974; Mutayoba et al., 1988). This study was designed to provide the pathological basis for some of the observed reproductive dysfunctions in cows infected with T. congolense. MATERIALS
AND METHODS
Six normally cycling Bunaji (80s indicrts) heifers were acquired from the Ahmadu Bello University Farm. On arrival at the Faculty of Veterinary Medicine, all the heifers were screened for brucellosis and leptospirosis. Baseline haematological data were obtained and their blood samples were examined for the presence of haemoparasites. The heifers were allowed a 2 month acclimatisation period, during which their oestrous activities were recorded. All the heifers were housed at the Faculty of Veterinary Medicine Research pens and fed grass hay supplemented with cotton seed cake and wheat offals before and throughout the experimental period. They were also given mineralised salt lick and water ad libitum. Four of the heifers were inoculated with approximately 1.5x lo6 T. congoIUW (strain 2295) via jugular venepuncture. The trypanosomes. which have been studied extensively (Sekoni, 1987), were obtained from the Department of Veterinary Parasitology and Entomology of Ahmadu Beilo University, Zaria. The parasites were stored in stabilates, preserved in 5% dimethyl sulphoxide and stored in liquid Atlogea. Prior to use, the stabi!atc v~srps inoculated into a sheep which subsequently developed clinical trypanosomiasis. Blood from the sheep was then used for the experimental infection. The two remaining heifers served as the uninfected controls. Following inoculation, blood samples were collected daily until parasitaemia was established and then twice weekly thereafter. In addition to determining parasitaemia, the blood samples were used to monitor anaemia and other haematological parameters. Body temperatures were taken between 8
and 9 a.m., before taking the blood samples, Changes in body condition were noted, while the reproductive activities of the heifers were monitored by once weekly rectal palpation of the genitalia, as recommended
by Zemjanis ( 1970).
GENITAL LESlONSlN TR,‘b?I.VOSO.I4 ~~O,\‘GOLFWEINFECTED
HEIFERS
The genitalia of the heifers killed when moribund, or at the end of the experimsnt as the controls, were harvested. The ovaries were weighed, then trimmed and processed for histopathofogical studies. AH the tissues were fixed in Bouin’s solution and paraffin-embedded sections were cut at 5 m on a sliding microtome and stained with Ehrlich’s haematoxylin and eosin (I-f & E ). Several histopathological sections were prepared for each heifer and studied in detail with a standard tight microscope. RESULTS
Ciinical obse.rvations The trypanosome had a pre-patent period of 5 days. The highest parasitaemia was recorded between the 10th and 20th day post-infection. Thereafter, parasitaemia fluctuated until the end of the experiment. All the infected heifers developed a severe form of trypanosomiasis, characterised by rapid weight loss. lethargy, weakness, lacrimation, roughened coat, pale mucous membranes, superficial lymphadenopathy and fluctustizg pyrexia, culminating in the heifers becoming moribund and their subsequent slaughter on Days 50, 71 and 113for the first, second, third and fuutih infected heifers, respectively. By Day 40. all the infected heifers had become anoestnts. A fluctuating rectal temperature of up to 40.2”C was recorded in all the infected heifers, while the control heifers had a normal rectal temperature (38.&38.6”C). This difference was significant (P
Gross puthologicalJindings in the genitalia The ovaries of the infected heifers were small and atrophic, devoid of any functional structures and had a mean weight of 8.04 2 2.2 g. In contrast, the ovaries of the control heifers had a mean weight of I 1.6 2 0.07 g (Table 1). In addition, the ovaries of the control heifers contained functional structures (follicles and corpora iutea: developing, developed or regressing). Similarly, the tubular genitalia of the infected heifers were atrophic and infantile in comparison to those of the control heifers. The uterine lumina were exaggerated and the walls had a rough conformation caused by the prominent vasculature and the atrophic myometrium.
D. OGWU AND C.0
4 TABLE
NIOKU
I
Heifer No.
Ovarian weigh1
Mt?aIl
5.9 7.2 a.6 8.9 9.8 9.5 6.6 6.8
7.05
11.5 12.4 11.0 Il.5
11.95
Mean weight of infected and conrrol + SD
Inficred L&l ovary Right ovary Left ovary Right cwuy Left ovary Kight ovary Left ovary Right ovary
399 102033 107 661
Conrrof 645
Left ovary Right ovary Left ovary Right ovary
649
SD. standard
8.04-c 2.2
8.75 9.65 6.1
11.61U.Oi
Il.25
deviation.
The infected heifer slaughtered on Day 50 had a relatively normal ovarian histology. There were, however, increased numbers of degenerating tertiary follicles and a complete absence of corpora lutea. In the infected heifers killed on Days 7 I and 113, the ovaries were characterisedby polycystic degeneration (Fig. I), multiple degeneration of tertiary follicles, the absence of developing, developed or regressing, corpora lutea and Graafian follicles, a decreased number of primordial and secondary follicles, and slight fibrosis of the cortex (Fig. 2). One striking feature of the ovaries of the infected heifers slaughtered on Day 113 was the proliferation of the rete ovarii. Severe inflammatory lesions were observed in the uterus of the infected heifers. Myzme?ris! and endometrial cellular in!Nra!ions, comprising mainly lymphocytes, macrophages and plasma cells, were observed. In addition, there were focal areas of cellular infiltration into the myometrium and periglandular areas (Fig. 3 ). As demonstrated in Fig. 4, immediately beneath the endometrial surface epithelium is a collection of stromal lymphocytes, macrophagesand plasma cells. There was also lymphoid proliferationin the endometrium of the infected heifers (Fig. 5). The two heifers slaughtered on Day I I3 showed, additionally, evidence of chronic endometritis characterised by distorted and atrophic endometrial glands (Fig. 6) and fibroplasia. Myometri~I atrophy, observed in all the infected heifers. was more severe
5
Fig. 1. Ovary ofan infectedheifer with cysticdegeneration (H&E; magnification, X 160).
Fig. 2. Ovary of an infected heifer. Note the paucity of primordial and secondary follicles. and slight fibrosis (H & E: mapi!ication. X 63).
in the three heifers slaughtered on Days 7 1 and 113. The muscular atrophy was accompanied by a prominent vascular proliferation and hypertrophy of the vascular wall (Fig. 7), culminating in some cases in endometrial vascular arteriosclerosis.
Fig. 3. IJkrus of an infectedheifer.Note the focalarea uf mononuclear cell infiltraticm in the endometrium(H & E; magnjtication,X 250).
Fig.4. U~crusof an infectedheifer.No& the diffusecellularintitrra~ionand glandularatrophy (l-l R:E: magnificnlion,x63).
UNITAL
LESli)NS IN TRYF!4hOSO>IfA CONGOLENSE INFECTED HElFERS
7
Fig. 5. Uterus of an infected heifer. Note the lymphoid hyperplasia in the endometriuimr(H& E: magnification. X 160).
Fig. 6. Uterus of an infected heifer showing glandularatrophy (H & E: magnification, X :160). In the cervix of the infected heifers there was cellular infiltration and a slight fibrosis. The mucosa was non-secretory and desquamated. The vaginal mucosa of the infected heifers was necrotic and sloughed There
D. OGWU AND C.O. NJOKU
Fig. 7. Uterus of an infected heiFer showing myometrirl atrophy, vascular hyperlrophy and fibroplasia (H %E: magnification, x 160).
were also areas ofcellular infiltration, again m&e up of mainly lymphocytes, macrophages and plasma cells (Figs 8 and 9 1.
GENITAL
LESIONS1N TAYP..N~SIM&ICONGDLENSE INFECTED HEIFERS
Fig. 9. Vagina of an infected heifer. Note the mononuclear cell infiltration tion, X 160).
(H&E; magnifica-
DISCUSSION
The clinical observations reported here are in agreement with those reported by Sekoni ( 1987) using the same strain of trypanosome. They are similar to our earlier observations with T. uivcucstrain Y58 (Ogwu et al., 1984). The mechanisms involved in the observed ovarian pathology require very careful study. In this investigation, the ovaries of the infected heifers were atrophic and devoid of functional structures, combined with multiple cystic degeneration of the follicles and first degree atresia of the Graalian follicles as describedby Rajakoski ( 1960). The pathogenesis of these ovarian lesions may not be unconnected with the hypothalamic-hypophyseal pathology observed in the infected heifers (D. Ogwu and C.O. Njoku, unpublished data, 1990 ) . While most of the lesions may be a direct effect of the endocrine dysfunction of the gonadotrophins, the direct effects of the trypanosome orgad nisms are yet to be explained. The cystic degeneration of the ovaries often reported in trypanosomal infections (Vohradsky, 1971; lsoun and Anosa, 1974; Mutayoba et al., 1988) are often thought to be due to a lack of preovulatory luteinising hormone surge (Luckins et al., 1986; Kutayoba et ai., 1988). However, the hypothalamic-hypophyseal pathology limiting the preovulatory surge should also have affected the follicular growth. Attempts should be made additionally to ascertain the effects of thyroid pathology on . k--=-n -*REPrwtir of the ova&r; this as h;-pt. 5,f roidrsm . :s ..“ll.. +n .Y ___I_ _,“.._ degeneration
in animals (Turner and Bagnara, 1976), and severe thyroid pathology has been described in trypanosomal infection (Mutayoba et al., 1988; D. Sgwu and C.Q. Njoku, unpublished data, 1990). Tbe observed atrophy of the tubular genitalia may be due to acyclic&y resulting from the ovarian pathology and the apparent lack or decrease of ovarian hormones. However, the more serious lesions of the tubular genitalia include the inflammatory changes, myometrial atrophy, and vascular and lymphoid hyperplasia. These are capable of causing infertility, even if the ovarian pathology were absent. Similarly, the observed cervicitis, when combined with vaginitis characterised by mucosal necrosis and sloughing, has grave reproductive consequence?. The significance or importance of the proliferation of the rete ovarii is not known, but may be associated with the mitogenic activities seen in try ranosomal infection (Esuruoso, 1976). The serious myometrial atrophy, vascular proliferation, hypertrophy and subsequent sclerosis, and the ability of these animals to restore their fertility following natural infection, require further scrutiny. Finally, attempts are being made to carry out the same investigation using trypanotolerant breeds like the N’dama which have been reported to have high residual fertility (Murray et al., 1981).
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