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Author Macchiarelli, Guido ♦ Nottola, Stefania A. ♦ Vizza, Enrico ♦ Familiari, Giuseppe ♦ Kikuta, Akio ♦ Murakami, Takuro ♦ Motta, Pietro M.
Source J-STAGE
Content type Text
Publisher International Society of Histology and Cytology
Language English
Abstract Rabbit ovarian microvasculature, with particular regard to developing and atretic follicles, was studied by scanning electron microscopy (SEM) of vascular corrosion casts. The microvascular network of the follicles was arranged in typical round plexuses of varying shape and size. Four different morphological types of vascular plexuses supplied the follicles: Type 1 (100-250μm in diameter) consisted of a simple net of thin capillaries that delimited a small empty central cavity. Type 2 (diameter>250μm) consisted of a multilayered capillary wall delimiting a large empty central cavity. This wall presented an inner layer made of uniformly distributed dilated and tortuous capillaries with numerous angiogenetic sprouts. Type 3 (diameter of 100-300μm) lacked the central cavity and comprised randomly arranged thin capillaries. Type 4 (diameter>250μm) consisted of a multilayered capillary wall delimiting a central cavity. Its inner layer was made of capillaries not homogeneous in size and course (thin in some areas, sinusoidal in others, sometimes highly dilated). In addition, the wall showed large interruptions (avascular areas) and focal invasion of the central cavity by newly formed vessels. Types 1 and 2 showed the gradual transformation of thin capillaries into sinusoids as has been demonstrated in evolutive follicles. Types 3 and 4, described here for the first time, probably represent the vascular supply to atretic follicles. In particular, Type 3 supplied follicles undergoing obliterating atretic degeneration, whereas Type 4 supplied atretic follicles with hypertrophy of the theca layer. In fact, follicular atresia is a pleiomorphic phenomenon which ends in a regression of the follicles (obliterant atresia), but which may induce a temporary follicular hyperactivation (luteinizing atresia). These changes in the microvasculature prelude the formation of the so called “interstitial gland of the ovary”. Furthermore, these data prove that: 1) both thecal capillary vasodilatation and angiogenetic processes basically support the gradual increase of ovarian blood flow during follicle growth; 2) microvascular changes of atretic follicles are possibly related to a type of inflammatory reaction since they seem to be a consequential rather than primary cause of atresia.
ISSN 09149465
Learning Resource Type Article
Publisher Date 1993-01-01
e-ISSN 13491717
Journal Archives of Histology and Cytology(aohc1988)
Volume Number 56
Issue Number 1
Page Count 12
Starting Page 1
Ending Page 12


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