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Estimated changes within the haemocyte population during the last larval and early pupal stages of Sarcophaga bullata Parker
J. Insect Physiol.,
1967, Vol. 13, pp. 645 to 646. Pergawwn Press Ltd. Printed in Great Britain
ESTIMATED CHANGES WITHIN THE HAEMQCYTE POPULATION DURING THE LAST LARVAL AND EARLY PUPAL STAGES OF SARCOPHAGA BULLATA PARKER* JACK Department of Entomology,
COLVARD
JONES
University of Maryland, College Park, Maryland,
(Received 23 December 1966) Abstract-No correlations were found to exist at any time among the calculated circulating populations of the three major types of haemocytes of Sarcophaga as they transform into pupae.
IN A previous study on the haemocytes of Sarcophaga bullata Parker differential and total haemocyte counts were presented along with haemolymph volumes expressed as percentages of the body weight during the last larval stage and during the act of pupation of this insect (JONES, 1956). These data were not presented in terms of the estimated numbers of the different types of haemocytes circulating within the entire haemocoele. Until this is done it is not possible to see quite so clearly the magnitude of changes that take place. During most of their life, Sarcophuga larvae feed on meat. Four to five days before pupation occurs, the larvae suddenly stop feeding and vigorously crawl away from the food, their crops stuffed with meat. As the larvae vigorously move about, their crops visibly empty of meat and fill with gas. Shortly after this, the gas bubble in the crop becomes invisible, the larvae become sluggish, and the spiracles at the rear end become a conspicuous caramel-brown. Within 3 hr the body contracts somewhat and the animal is then incapable of locomotion and the external manifestation of pupation has begun. A pale-orange flush can be seen at the posterior end of the motionless animal and the entire cuticle is an orange colour in about 30 min. The orange changes to a tan, thence into a reddish brown (in 6 hr), and finally becomes a dark reddish black. Just before the larvae stop feeding, their haemolymph volume is 68.1 ~1. During the crawling crop-full stage the haemolymph volume is estimated to be 80.8 ~1. As the crop empties of meat, the haemolymph volume is calculated to be 66-68 ~1. The haemolymph volume of larvae with caramel-brown spiracles is 69.2 ~1. Shortly after the insect contracts and becomes motionless, the haemolymph volume is 47-49 ~1. When the puparium is brown, the haemolymph volume *This work was sponsored by N.I.H. Grant HE-5193 and by Career Development Award K3-GM 21,529. Scientific Article No. A1320, Contribution No. 3866, of the Maryland Agricultural Experiment Station. 645 42
646
JACKCOLVARDJONES
is seen to remain essentially the same (48.5 ~1). When the puparium is dark reddish black, the amount of haemolymph is approximately 30 ~1. When the amount of haemolymph within the various stages is multiplied by the number of haemocytes per ~1 (JONES, 1956), it can be calculated that there are 514,155 haemocytes in circulation in the larvae which are still feeding on meat, and that by the time they reach the brown-spiracle stage prior to the act of pupation, the number of haemocytes in circulation has increased to a value of 2,335,500 cells, a 4*5-fold increase. Within the next 3 hr 1,376,302 haemocytes disappear from the circulating haemolymph. When the percentages of the three kinds of haemocytes are multiplied by the estimated haemocyte population, it can be seen that enormous numbers of plasmatocytes and granular haemocytes enter the circulation between the crawling cropfull stage and the brown-spiracle stage (Table 1). It is very evident from Table 1 that there are no correlations between changes in the populations of the different haemocytes at any time and this is interpreted to mean that neither granular haemocytes nor spherule cells are being derived from plasmatocytes. TABLE ~-ESTIMATED NUMBERS OFDIFFERENT TYPESOFHAEMOCYTES CIRCULATING WITHINTHE HAEMOCOFLE OF UNFIXESSarcophaga bullata DURINGTHE LAST LARVALAND EARLYPUPAL STAGES Numbers circulating in the haemocoele
Status
Plasmatocytes
Granular haemocytes
Spherule cells
Total
Crop full of meat Crawling, crop full Crop emptying Crop emptied Brown spiracle White ‘pupae’ Brown ‘pupae’ Black ‘pupae’
355,795 273,241 362,523 646,852 866,470 461,374 221,071 380,498
140,364 382,122 658,655 887,685 1,466,694 494,946 323,439 156,199
17,995 38,142 32,669 9263 2335 2877 0 3243
415,154 693,505 1,053,847 1,543,800 2,335,499 959,197 544,510 539,940
The evidence presented here and elsewhere (JONES, 1956) definitely does not support the claims of GUPTA and SUTHERLAND(1966) that plasmatocytes, granular haemocytes, and spherule cells normally transform into one another, or that these types change back and forth according to the need of the insect, or that the plasmatocyte is a pluripotential cell normally capable of turning into any of the other types. On the contrary, the calculations given here suggest that plasmatocytes, granular haemocytes, and spherule cells each constitute highly distinct cell lines in Surco-
phaga bullata. REFERENCES GUPTA A. P. and SUTHERLAND D. J. (1966) In vitro transformations of the insect plasmatocyte in some insects. J. Insect Physiol. 12, 1369-l 375. JONESJ. C. (1956) The hemocytes of Sarcophaga bullata Parker. J. Morph. 99, 233-257.
1967, Vol. 13, pp. 645 to 646. Pergawwn Press Ltd. Printed in Great Britain
ESTIMATED CHANGES WITHIN THE HAEMQCYTE POPULATION DURING THE LAST LARVAL AND EARLY PUPAL STAGES OF SARCOPHAGA BULLATA PARKER* JACK Department of Entomology,
COLVARD
JONES
University of Maryland, College Park, Maryland,
(Received 23 December 1966) Abstract-No correlations were found to exist at any time among the calculated circulating populations of the three major types of haemocytes of Sarcophaga as they transform into pupae.
IN A previous study on the haemocytes of Sarcophaga bullata Parker differential and total haemocyte counts were presented along with haemolymph volumes expressed as percentages of the body weight during the last larval stage and during the act of pupation of this insect (JONES, 1956). These data were not presented in terms of the estimated numbers of the different types of haemocytes circulating within the entire haemocoele. Until this is done it is not possible to see quite so clearly the magnitude of changes that take place. During most of their life, Sarcophuga larvae feed on meat. Four to five days before pupation occurs, the larvae suddenly stop feeding and vigorously crawl away from the food, their crops stuffed with meat. As the larvae vigorously move about, their crops visibly empty of meat and fill with gas. Shortly after this, the gas bubble in the crop becomes invisible, the larvae become sluggish, and the spiracles at the rear end become a conspicuous caramel-brown. Within 3 hr the body contracts somewhat and the animal is then incapable of locomotion and the external manifestation of pupation has begun. A pale-orange flush can be seen at the posterior end of the motionless animal and the entire cuticle is an orange colour in about 30 min. The orange changes to a tan, thence into a reddish brown (in 6 hr), and finally becomes a dark reddish black. Just before the larvae stop feeding, their haemolymph volume is 68.1 ~1. During the crawling crop-full stage the haemolymph volume is estimated to be 80.8 ~1. As the crop empties of meat, the haemolymph volume is calculated to be 66-68 ~1. The haemolymph volume of larvae with caramel-brown spiracles is 69.2 ~1. Shortly after the insect contracts and becomes motionless, the haemolymph volume is 47-49 ~1. When the puparium is brown, the haemolymph volume *This work was sponsored by N.I.H. Grant HE-5193 and by Career Development Award K3-GM 21,529. Scientific Article No. A1320, Contribution No. 3866, of the Maryland Agricultural Experiment Station. 645 42
646
JACKCOLVARDJONES
is seen to remain essentially the same (48.5 ~1). When the puparium is dark reddish black, the amount of haemolymph is approximately 30 ~1. When the amount of haemolymph within the various stages is multiplied by the number of haemocytes per ~1 (JONES, 1956), it can be calculated that there are 514,155 haemocytes in circulation in the larvae which are still feeding on meat, and that by the time they reach the brown-spiracle stage prior to the act of pupation, the number of haemocytes in circulation has increased to a value of 2,335,500 cells, a 4*5-fold increase. Within the next 3 hr 1,376,302 haemocytes disappear from the circulating haemolymph. When the percentages of the three kinds of haemocytes are multiplied by the estimated haemocyte population, it can be seen that enormous numbers of plasmatocytes and granular haemocytes enter the circulation between the crawling cropfull stage and the brown-spiracle stage (Table 1). It is very evident from Table 1 that there are no correlations between changes in the populations of the different haemocytes at any time and this is interpreted to mean that neither granular haemocytes nor spherule cells are being derived from plasmatocytes. TABLE ~-ESTIMATED NUMBERS OFDIFFERENT TYPESOFHAEMOCYTES CIRCULATING WITHINTHE HAEMOCOFLE OF UNFIXESSarcophaga bullata DURINGTHE LAST LARVALAND EARLYPUPAL STAGES Numbers circulating in the haemocoele
Status
Plasmatocytes
Granular haemocytes
Spherule cells
Total
Crop full of meat Crawling, crop full Crop emptying Crop emptied Brown spiracle White ‘pupae’ Brown ‘pupae’ Black ‘pupae’
355,795 273,241 362,523 646,852 866,470 461,374 221,071 380,498
140,364 382,122 658,655 887,685 1,466,694 494,946 323,439 156,199
17,995 38,142 32,669 9263 2335 2877 0 3243
415,154 693,505 1,053,847 1,543,800 2,335,499 959,197 544,510 539,940
The evidence presented here and elsewhere (JONES, 1956) definitely does not support the claims of GUPTA and SUTHERLAND(1966) that plasmatocytes, granular haemocytes, and spherule cells normally transform into one another, or that these types change back and forth according to the need of the insect, or that the plasmatocyte is a pluripotential cell normally capable of turning into any of the other types. On the contrary, the calculations given here suggest that plasmatocytes, granular haemocytes, and spherule cells each constitute highly distinct cell lines in Surco-
phaga bullata. REFERENCES GUPTA A. P. and SUTHERLAND D. J. (1966) In vitro transformations of the insect plasmatocyte in some insects. J. Insect Physiol. 12, 1369-l 375. JONESJ. C. (1956) The hemocytes of Sarcophaga bullata Parker. J. Morph. 99, 233-257.