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Re-innervation pattern of heterotopically transposed lingual flaps
276
]. max.-fac. Surg. 14 (1986)
J. max.-fac. Surg. 14 (1986) 276-280 © Georg Thieme Verlag Stuttgart • New York
Summary
Re-lnnervation Pattern of Heterotopically Transposed Lingual Flaps Roberto Gamolettil, Maria Grazia Petruccioli 2, Roberto B rusati 1, Bruno G iannii 2, Nicola Mannucci 1, Alberto Miani 2, Giuliano Pizzini 2 1Department of Maxillo-Facial Surgery (Head: Prof. R. Brusati, M.D.), University and Hospital of Parma 2Institute of Anatomy, (Head: Prof. A. Miani, M.D.), University of Milan, Italy
Submitted 31.10. 1985; accepted 13.11. 1985
Key-Words Lingual flap - Re-innervation - Sensory receptors Tongue
Introduction Pedicled tongue flaps have proved to be an effective procedure, in one or two stages, for the repair of tissue loss defects in the oral cavity when regional flaps from the head and neck are inappropriate for various reasons. The use of a lingual flap with a dorsal pedicle was first described by Klopp and Shurter in 1956 for the repair of an oral defect following the removal of a tonsillar cancer. After this report, lingual flaps have been used for the repair of fistulae of the hard palate (Guerrero-Santos and Ahamirano, 1966; Jackson, 1972), for the closure of defects of the floor of mouth and alveolar crest (Papaioannou and Farr, 1966; Calamel, 1973), for the reconstruction of the soft palate, tonsillar region (ConIey et al., 1957) cheek (Ganguli, 1968; Bakamjian, 1972) and for resurfacing the lips (Bakamjian, 1964; Guerrero Santos et al., 1964; Cadenat et al., 1973; Ortiz-Monasterio and Factor, 1980). In 1980 Brusati reported on 15 cases of various oral cavity defects repaired with lingual flaps. The use of lingual tissue for the repair of tissue defects in such a variety of sites in the oral cavity is feasible using flaps with different types of pedicle (anterior, posterior, double) and confirms the striking versatility of lingual flaps. This latter characteristic relies upon the rich vascular supply of tongue flaps as reported in detail by Cadenat et al. (1973). On the other hand no histological investigation has been carried out concerning the long-term fate of these flaps in respect of re-vascularization and re-innervation from the
Fig. 1 a
Pedicled tongue flaps have proved to be an effective method of repairing defects due to tissue loss in the oral cavity. No histological investigations have been done in respect of the longterm fate of these flaps after section of their nutrient pedicle. The histological pattern of the re-innervation process of heterotopically transposed lingual flaps in the oral cavity is evaluated in this paper. Two cases are reported: in the first, the tongue flap was used to repair the vermilion of the lower lip and in the second, for the closure of a post-traumatic defect of the hard palate. The histological findings are similar in the two cases: myelinated and unmyelinated fibres, free nerve endings and encapsulated receptors are present.
Fig. 1 b
surrounding tissues following section of the nutrient pedicle. The aim of this paper is to evaluate the histological pattern of the re-innervation process of heterotopically transposed lingual flaps in the oral cavity.
Material and Methods Specimens of lingual flaps have been obtained from two patients 2 and 3 years respectively after the transposing operation. In the first patient a bipedicled anterior lingual flap has been used to resurface the vermilion of the lower lip after the removal of multicentric tumour lesions (Fig. 1); in the second patient a posteriorly based flap was raised from the dorsum of the tongue and used to close a large oro-antral post-traumatic defect in the hard palate. The biopsy specimens were obtained with a scalpel, cut into pieces and immediately fixed in a 3 % solution of glutaraldehyde in 0.12 M-phosphate buffer, post-fixed in a solution of osmium tetroxide in 0.18 M-phosphate buffer, dehydrated in graded alcohols and embedded in Epon 812. Semi-thin sections were stained with toluidine blue and studied under the light microscope. Thin sections were obtained with a Reichert Om U3 ultratome, collected on copper grids, stained with uranyl acetate and lead citrate and studied under a Jeol 100 and a Siemens Elmiskop transmission electron microscopes.
Fig. 1 Case 1 : a) Bipedicled anterior lingual flap sutured to the vermilion defect; b) late postoperative appearance of the flap.
Re-Innervation Pattern of Heterotopically Transposed Lingual Flaps
Fig, 2 Case 1: light micrograph of a semi-thin section of the tongue flap showing the epithelium (E) and the subepithelial connective tissue (C) in which nerve plexuses are easily visible (arrows) (x 400).
J. max.-fac. Surg. 14 (1986)
277
Fig. 3 Case 1 : transverse section of a very complex nerve bundle formed mainly by myelinated fibres (M) surrounded and divided by thin processes of connective tissue cells (arrows) (x 4000).
Results
Fig. 4 Transverse section of a nerve bundle similar to that observed in Fig. 3 but made up of small unmyelinated fibres (arrows) (x 7000): Case 1.
The light and transmission electron microscope evaluation of the specimens has disclosed a series of common morphological aspects in spite of the differences in raising and transposing the two flaps. We have, however, found larger nerve bundles and an increased density of nerve receptor terminals in the specimens taken from the first patient. Light microscopy showed the presence of a normal squamous pluri-stratified epithelium lying on a sub-epithelial connective tissue rich in blood vessels and nerve bundles. These latter are particularly abundant towards the subepithelial portion and are arranged multi-directionally so as to give rise to a distinct sub-epithelial plexus: this morphological appearance is particularly evident in the specimens from the first case (Fig. 2). Transmission electron microscope observations confirm the presence of myelinated fibres arranged in bundles of different diameters within the sub-epithelial connective tissue; unmyelinated fibres and receptor structures are also present. Myelinated fibres were present in specimens from the first case as single elements and more often as complex bundles because they consisted of groups (4-5 myelinated elements
278
J. max.-fac. Surg. 14 (1986)
R. Gamoletti et al.
Fig. 5 Case 2: low-power electron micrograph of the tongue flap. in the subepithelial connective tissue there are many unmyelinated fibres transversely or longitudinally sectioned (arrows) (x 6000).
Fig. 6 a
Fig. 6 b
Fig. 6 c
Fig. 6 Free nerve endings in the subepithelial connective tissue of the lingual flap: a) a collection of nerve endings (E) surrounded by the basal membrane (x 12000): Case 1; b) Case 2: afree nerve ending
filled with granular and agranular vesicles (x 15000); c) Case 1: a free nerve ending filled with mitochondria and closely associated with a Schwann ceil (x 10000).
in each group) separated from each other by a particular rearrangement of the fibroblasts (Fig. 3). The cytoplasmic process of the fibroblasts create a segmentation of the nerve bundles that resembles the one produced by the connective tissue in the somatic nerves. Unmyelinated fibres are abundant and often arranged into complex bundles (Fig. 4). Free nerve endings and encapsulated receptors have been found in the specimens from the first case. Transmission electron microscope observation of the specimens from the second case have disclosed fewer myelinated
and unmyelinated fibres that sometimes form small bundles of 2-3 fibres each without any morphologic peculiarity (Fig. S). The free nerve endings that we have found especially in the specimens from the first case consist of a terminal swelling of the nerve fibres containing a great accumulation of mitochondria and clear vesicles within the axoplasm: they are surrounded either by a Schwann cell containing several pinocytotic vesicles inside the cytoplasm or by a basal membrane (Fig. 6). The encapsulated receptors are complex structures consi-
Re-Innervation Pattern of Heterotopically Transposed Lingual Flaps
J. max.-fac. Surg. 14 (1986)
279
Fig. 7 a
Fig. 7 b
Fig. 7 Case 1 : an encapsulated receptor with a complex lameltar capsule: a) three nerve endings (arrows) are ensheathed by many layers of flattened cells: the inner core is formed by Schwann cells (S) and the outer core by fibroblasts (F) (x 6000); b) detail of a) showing
two nerve endings (arrows) characterized by a high electron-dense cytoplasm filled with mitochondria, agranular vesicles and multivesicular bodies (asterisk) x 15 000).
sting of 1-3 nerve endings containing an accumulation of mitochondria, mainly clear vesicles and multivesicular bodies; the cytoplasmic matrix is very dense as a rule (Fig. 7). The nonmyelinated branches are surrounded by perineural receptor cells. The inner cells are thinned Schwann cells covered by the basal membrane while the outer ones are perineural capsular elements that in the present case do not give rise to a continuous capsule. Between these two layers, a subcapsular space is present containing fibroblasts and collagen fibres. In all the specimens we have found regenerative evidence in the myelinated and unmyelinated fibres: the altered ratio between the axonal diameter and thickness of its myelin sheath, a single Schwann cell surrounding several unmyelihated axons, the axolemma of the myelinated fibres rich in filaments, tubules and mitochondria (Fig. 8).
innervation with the presence of myelinated fibres and receptor structures. The nerve fibres, however, show some morphological features typical of regenerative processes still in the process of completion: the altered ratio between the axonal diameter and thickness of its myelin sheath, the abundant filaments and tubules within the axolemma, the great number of small diameter unmyelinated fibres surrounded by a single Schwann cell. All these findings can be explained by the great variation in regeneration times in the nervous system according to species and anatomical sites as reported in the literature (Lee, 1930; Butson, 1950; Liu and Chambers, 1958; Raisman et al., 1974; Bray and Aguayo, 1974). It is worth noting, even if expected, the occurrence of both free nerve endings and encapsulated receptors as morphological evidence of functional sensory recovery. The free nerve endings found in our specimens are similar to these described bz Chouchkov (1972), Halata (1975) and Zocchi et al. (1982) in the human epidermis. The encapsulated receptors described in the present paper showed the morphological characteristics of encapsulated receptors with an asymmetrical inner core and called Krause bulbs (Chouchkov, 1978): such types of receptors found and described for the first time in the external genitals, have been subsequently described in the oral mucosa and pharynx (Chouchkov, 1965; Kadenoff and Chouchkov, 1967). The
Discussion and Conclusions The complete integration of the transposed lingual flaps into the recipient site, as observed clinically, is in agreement with the morphological and ultrastructural findings of a good re-innervation process in the flaps following the section of their pedicle. Two to three years after the section of the pedicle both flaps presented herein showed a well advanced process of re-
2 80
J. max.-fac. Surg. 14 (1986)
Fig. 8
Case 2: regenerative features of the nerve fibres: a thin myelin sheath surround a large diameter axon (asterisk) full of neurofilaments and mitochondria ( x 12 000)
v a r i a t i o n of the r e c e p t o r density f o u n d in the specimens f r o m the t w o cases e v a l u a t e d for this study can be e x p l a i n e d a c c o r d i n g to the differences in a n a t o m i c a l site and substrate e n c o u n t e r e d by the r e g e n e r a t i n g a x o n a l p o p u l a t i o n as conf i r m e d by the literature ( C h o u c h k o v , 1979; M a c k e l et al., 1983). In fact the specimens f r o m the first case w e r e taken f r o m a lingual flap t r a n s p o s e d to a richly v a s c u l a r i z e d and i n n e r v a t e d site such as the l o w e r lip. T h e second case on the o t h e r h a n d is the result of ligual flap t r a n s p o s i t i o n c o v e r i n g p o s t - t r a u m a t i c scarred tissue in the h a r d palate w h e r e sensory elements are fewer.
References Bakamjian, V. Y.: Use of tongue flaps in lower lip reconstruction. Brit. J. Plast. Surg. 17 (1964) 76 Bakamjian, V. Y.: Anteriorly and posteriorly based pedicle flaps from the dorsum of the tongue. In: Conley J. and Dickinson, J. T.: Plastic and Reconstructive Surgery of the and Neck. Thieme, Stuttgart 1972, p. 158
R. G a m o l e t t i et al.: R e - I n n e r v a t i o n Pattern Bray, G. M., A. Y. Aguayo: Regeneration of peripheral unmyelinated nerves. Fate of axonal sprouts which develop after injury. J. Anat. 117 (1974) 517 Brusati, R.: I lembi linguali in chirurgia ricostruttiva labio-orofaringea. Riv. ltal. Chit. Plast. 3 (1980) 123 Butson, A. R. C.: Regeneration of the cervical sympathetic. Brit. J. Surg. 38 (1950) 223 Cadenat, H., R. CombelIes, M. Fable: Lambeaux de langue, vascularisation, morphologie et utilisation. Ann. Chit. Plast. 18 (1973) 223 Calamel, P. M.: The median transit tongue flaps. Plast. Reconstr. Surg. 51 (1973) 315 Chouchkov, C.: Vergleichende Darstellung der afferenten lnnervation der den Waldeyerschen Rachenring bildenden Tonsillen beim Menschen. Z. Mikr.-Anat. Forsch. 74 (1965) 1 Chouchkov, C.: On the fine structure of free nerve endings in human digital skin oral cavity and rectum. Z. Mikr.-Anat. Forsch. 86 (1972) 273 Chouchkov, C.: Cutaneous Receptors. Ultrastructure and morphological classification. In: Advances in Anatomy, Embryology and Cell Biology. Springer, Berlin-Heidelberg-New York. 54 (1978) 9 Chouchkov, C.: Degeneration and regeneration of some mechanoreceptors. An ultrastructure study. IV. Ultrastructure of reinnervated Pacinian corpuscles. Z. Mikr.-Anat. Forsch. 94 (1979) 433 Conley, J. J., F. Amnesti, M. K. Pierce: The use of tongue flaps in head and neck surgery. Surgery. 41 (1957) 745 Ganguli, A.: Use of tongue flap to line cheek defects in surgery for cancer. Plast. Reconstr. Surg. 41 (1968) 390 Guerrero-Santos, J., R. Vasquez-Pallares, A. Veram, P. Machain, A. Castaneda: The tongue flap in reconstruction of the lip. Trans. Third. Internat. Congr. Plast. Surg., Excepta Medica Foundation, Amsterdam (1964) p. 1055 Guerrero-Santos, J., J. T. Altamirano: Use of lingual flaps in repair of fistulas of the hard and soft palate. Plast. Reconstr. Surg. 38 (1966) 123 Halata, Z.: The mechanoreceptors of the mamalian skin. Ultrastructure and morphological classification. In: Advances in Anatomy, Embryology and Cell Biology. Springer, Berlin-Heidelberg-New York 50 (1975) 5 Jackson, I. T.: Use of the tongue flaps to resurface lip defects and close palatal fistulae in children. Plast. Reconstr. Surg. 49 (1972) 537 Kadenoff, D., C. Chouchkov: Die afferente Innervation der Pars nasalis pharyngis beim Menschen. Z. Mikr.-Anat. Forsch. 73 (1967) 212 Klopp, C. T., M. Schurter: The surgical treatment of cancer of the soft palate and tonsil. Cancer 9 (1956) 1239 Liu, C.N., W. W. Chambers: intraspinal sprouting of dorsal root axons. Arch. Neurol. 79 (1958) 46 Lee, F. C.: The regeneration of sympathetic nerve fibers. Ass. Res. nerv. merit. Dis. 9 (1930) 417 Mackel, R., E. Kunesch, F. Waldhor, A. Struppler: Reinnervation of mechanoreceptors in the hm-nan glabrus skin following peripheral nerve repair. Brain. Res. 268 (1983) 49 Ortiz-Monasterio, F., R. Factor: Early definitive treatment of electric burns of the month. Plast. Reconstr. Surg. 65 (1980) 169 Papaioannou, A. N., H. W. Farr: Reconstruction of the floor of the mouth by a pedicled tongue flap. Surg. Gynec. Obstet. 122 (1966) 807 Raisman, G., P. M. Field, A. J. C. Ostberg, L. L. Iversen, R. E. Zigmond: A quantitative ultrastrnctural and biochemical analysis of the process of reinnervation of the superior cervical ganglion in the adult rat. Brain. Res. 71 (1974) 1 Zocchi, M., M. Stella, S. Teich-Alasia: Les rdcepteurs sensitifs cutands: Etude morphologique et fonctionnelle de la resensibilisation des lambeaux cutan&. Ann. Chir. Plast. 27 (1982) 375 Prof. M. G. Petruccioli, M.D. Institute of Anatomy, University of Milan Via Mangiagalli 31 1-20133 Milan, Italy
]. max.-fac. Surg. 14 (1986)
J. max.-fac. Surg. 14 (1986) 276-280 © Georg Thieme Verlag Stuttgart • New York
Summary
Re-lnnervation Pattern of Heterotopically Transposed Lingual Flaps Roberto Gamolettil, Maria Grazia Petruccioli 2, Roberto B rusati 1, Bruno G iannii 2, Nicola Mannucci 1, Alberto Miani 2, Giuliano Pizzini 2 1Department of Maxillo-Facial Surgery (Head: Prof. R. Brusati, M.D.), University and Hospital of Parma 2Institute of Anatomy, (Head: Prof. A. Miani, M.D.), University of Milan, Italy
Submitted 31.10. 1985; accepted 13.11. 1985
Key-Words Lingual flap - Re-innervation - Sensory receptors Tongue
Introduction Pedicled tongue flaps have proved to be an effective procedure, in one or two stages, for the repair of tissue loss defects in the oral cavity when regional flaps from the head and neck are inappropriate for various reasons. The use of a lingual flap with a dorsal pedicle was first described by Klopp and Shurter in 1956 for the repair of an oral defect following the removal of a tonsillar cancer. After this report, lingual flaps have been used for the repair of fistulae of the hard palate (Guerrero-Santos and Ahamirano, 1966; Jackson, 1972), for the closure of defects of the floor of mouth and alveolar crest (Papaioannou and Farr, 1966; Calamel, 1973), for the reconstruction of the soft palate, tonsillar region (ConIey et al., 1957) cheek (Ganguli, 1968; Bakamjian, 1972) and for resurfacing the lips (Bakamjian, 1964; Guerrero Santos et al., 1964; Cadenat et al., 1973; Ortiz-Monasterio and Factor, 1980). In 1980 Brusati reported on 15 cases of various oral cavity defects repaired with lingual flaps. The use of lingual tissue for the repair of tissue defects in such a variety of sites in the oral cavity is feasible using flaps with different types of pedicle (anterior, posterior, double) and confirms the striking versatility of lingual flaps. This latter characteristic relies upon the rich vascular supply of tongue flaps as reported in detail by Cadenat et al. (1973). On the other hand no histological investigation has been carried out concerning the long-term fate of these flaps in respect of re-vascularization and re-innervation from the
Fig. 1 a
Pedicled tongue flaps have proved to be an effective method of repairing defects due to tissue loss in the oral cavity. No histological investigations have been done in respect of the longterm fate of these flaps after section of their nutrient pedicle. The histological pattern of the re-innervation process of heterotopically transposed lingual flaps in the oral cavity is evaluated in this paper. Two cases are reported: in the first, the tongue flap was used to repair the vermilion of the lower lip and in the second, for the closure of a post-traumatic defect of the hard palate. The histological findings are similar in the two cases: myelinated and unmyelinated fibres, free nerve endings and encapsulated receptors are present.
Fig. 1 b
surrounding tissues following section of the nutrient pedicle. The aim of this paper is to evaluate the histological pattern of the re-innervation process of heterotopically transposed lingual flaps in the oral cavity.
Material and Methods Specimens of lingual flaps have been obtained from two patients 2 and 3 years respectively after the transposing operation. In the first patient a bipedicled anterior lingual flap has been used to resurface the vermilion of the lower lip after the removal of multicentric tumour lesions (Fig. 1); in the second patient a posteriorly based flap was raised from the dorsum of the tongue and used to close a large oro-antral post-traumatic defect in the hard palate. The biopsy specimens were obtained with a scalpel, cut into pieces and immediately fixed in a 3 % solution of glutaraldehyde in 0.12 M-phosphate buffer, post-fixed in a solution of osmium tetroxide in 0.18 M-phosphate buffer, dehydrated in graded alcohols and embedded in Epon 812. Semi-thin sections were stained with toluidine blue and studied under the light microscope. Thin sections were obtained with a Reichert Om U3 ultratome, collected on copper grids, stained with uranyl acetate and lead citrate and studied under a Jeol 100 and a Siemens Elmiskop transmission electron microscopes.
Fig. 1 Case 1 : a) Bipedicled anterior lingual flap sutured to the vermilion defect; b) late postoperative appearance of the flap.
Re-Innervation Pattern of Heterotopically Transposed Lingual Flaps
Fig, 2 Case 1: light micrograph of a semi-thin section of the tongue flap showing the epithelium (E) and the subepithelial connective tissue (C) in which nerve plexuses are easily visible (arrows) (x 400).
J. max.-fac. Surg. 14 (1986)
277
Fig. 3 Case 1 : transverse section of a very complex nerve bundle formed mainly by myelinated fibres (M) surrounded and divided by thin processes of connective tissue cells (arrows) (x 4000).
Results
Fig. 4 Transverse section of a nerve bundle similar to that observed in Fig. 3 but made up of small unmyelinated fibres (arrows) (x 7000): Case 1.
The light and transmission electron microscope evaluation of the specimens has disclosed a series of common morphological aspects in spite of the differences in raising and transposing the two flaps. We have, however, found larger nerve bundles and an increased density of nerve receptor terminals in the specimens taken from the first patient. Light microscopy showed the presence of a normal squamous pluri-stratified epithelium lying on a sub-epithelial connective tissue rich in blood vessels and nerve bundles. These latter are particularly abundant towards the subepithelial portion and are arranged multi-directionally so as to give rise to a distinct sub-epithelial plexus: this morphological appearance is particularly evident in the specimens from the first case (Fig. 2). Transmission electron microscope observations confirm the presence of myelinated fibres arranged in bundles of different diameters within the sub-epithelial connective tissue; unmyelinated fibres and receptor structures are also present. Myelinated fibres were present in specimens from the first case as single elements and more often as complex bundles because they consisted of groups (4-5 myelinated elements
278
J. max.-fac. Surg. 14 (1986)
R. Gamoletti et al.
Fig. 5 Case 2: low-power electron micrograph of the tongue flap. in the subepithelial connective tissue there are many unmyelinated fibres transversely or longitudinally sectioned (arrows) (x 6000).
Fig. 6 a
Fig. 6 b
Fig. 6 c
Fig. 6 Free nerve endings in the subepithelial connective tissue of the lingual flap: a) a collection of nerve endings (E) surrounded by the basal membrane (x 12000): Case 1; b) Case 2: afree nerve ending
filled with granular and agranular vesicles (x 15000); c) Case 1: a free nerve ending filled with mitochondria and closely associated with a Schwann ceil (x 10000).
in each group) separated from each other by a particular rearrangement of the fibroblasts (Fig. 3). The cytoplasmic process of the fibroblasts create a segmentation of the nerve bundles that resembles the one produced by the connective tissue in the somatic nerves. Unmyelinated fibres are abundant and often arranged into complex bundles (Fig. 4). Free nerve endings and encapsulated receptors have been found in the specimens from the first case. Transmission electron microscope observation of the specimens from the second case have disclosed fewer myelinated
and unmyelinated fibres that sometimes form small bundles of 2-3 fibres each without any morphologic peculiarity (Fig. S). The free nerve endings that we have found especially in the specimens from the first case consist of a terminal swelling of the nerve fibres containing a great accumulation of mitochondria and clear vesicles within the axoplasm: they are surrounded either by a Schwann cell containing several pinocytotic vesicles inside the cytoplasm or by a basal membrane (Fig. 6). The encapsulated receptors are complex structures consi-
Re-Innervation Pattern of Heterotopically Transposed Lingual Flaps
J. max.-fac. Surg. 14 (1986)
279
Fig. 7 a
Fig. 7 b
Fig. 7 Case 1 : an encapsulated receptor with a complex lameltar capsule: a) three nerve endings (arrows) are ensheathed by many layers of flattened cells: the inner core is formed by Schwann cells (S) and the outer core by fibroblasts (F) (x 6000); b) detail of a) showing
two nerve endings (arrows) characterized by a high electron-dense cytoplasm filled with mitochondria, agranular vesicles and multivesicular bodies (asterisk) x 15 000).
sting of 1-3 nerve endings containing an accumulation of mitochondria, mainly clear vesicles and multivesicular bodies; the cytoplasmic matrix is very dense as a rule (Fig. 7). The nonmyelinated branches are surrounded by perineural receptor cells. The inner cells are thinned Schwann cells covered by the basal membrane while the outer ones are perineural capsular elements that in the present case do not give rise to a continuous capsule. Between these two layers, a subcapsular space is present containing fibroblasts and collagen fibres. In all the specimens we have found regenerative evidence in the myelinated and unmyelinated fibres: the altered ratio between the axonal diameter and thickness of its myelin sheath, a single Schwann cell surrounding several unmyelihated axons, the axolemma of the myelinated fibres rich in filaments, tubules and mitochondria (Fig. 8).
innervation with the presence of myelinated fibres and receptor structures. The nerve fibres, however, show some morphological features typical of regenerative processes still in the process of completion: the altered ratio between the axonal diameter and thickness of its myelin sheath, the abundant filaments and tubules within the axolemma, the great number of small diameter unmyelinated fibres surrounded by a single Schwann cell. All these findings can be explained by the great variation in regeneration times in the nervous system according to species and anatomical sites as reported in the literature (Lee, 1930; Butson, 1950; Liu and Chambers, 1958; Raisman et al., 1974; Bray and Aguayo, 1974). It is worth noting, even if expected, the occurrence of both free nerve endings and encapsulated receptors as morphological evidence of functional sensory recovery. The free nerve endings found in our specimens are similar to these described bz Chouchkov (1972), Halata (1975) and Zocchi et al. (1982) in the human epidermis. The encapsulated receptors described in the present paper showed the morphological characteristics of encapsulated receptors with an asymmetrical inner core and called Krause bulbs (Chouchkov, 1978): such types of receptors found and described for the first time in the external genitals, have been subsequently described in the oral mucosa and pharynx (Chouchkov, 1965; Kadenoff and Chouchkov, 1967). The
Discussion and Conclusions The complete integration of the transposed lingual flaps into the recipient site, as observed clinically, is in agreement with the morphological and ultrastructural findings of a good re-innervation process in the flaps following the section of their pedicle. Two to three years after the section of the pedicle both flaps presented herein showed a well advanced process of re-
2 80
J. max.-fac. Surg. 14 (1986)
Fig. 8
Case 2: regenerative features of the nerve fibres: a thin myelin sheath surround a large diameter axon (asterisk) full of neurofilaments and mitochondria ( x 12 000)
v a r i a t i o n of the r e c e p t o r density f o u n d in the specimens f r o m the t w o cases e v a l u a t e d for this study can be e x p l a i n e d a c c o r d i n g to the differences in a n a t o m i c a l site and substrate e n c o u n t e r e d by the r e g e n e r a t i n g a x o n a l p o p u l a t i o n as conf i r m e d by the literature ( C h o u c h k o v , 1979; M a c k e l et al., 1983). In fact the specimens f r o m the first case w e r e taken f r o m a lingual flap t r a n s p o s e d to a richly v a s c u l a r i z e d and i n n e r v a t e d site such as the l o w e r lip. T h e second case on the o t h e r h a n d is the result of ligual flap t r a n s p o s i t i o n c o v e r i n g p o s t - t r a u m a t i c scarred tissue in the h a r d palate w h e r e sensory elements are fewer.
References Bakamjian, V. Y.: Use of tongue flaps in lower lip reconstruction. Brit. J. Plast. Surg. 17 (1964) 76 Bakamjian, V. Y.: Anteriorly and posteriorly based pedicle flaps from the dorsum of the tongue. In: Conley J. and Dickinson, J. T.: Plastic and Reconstructive Surgery of the and Neck. Thieme, Stuttgart 1972, p. 158
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