title: Enrichment of the stages of the seminiferous epithelium in vitamin A-replaced-vitamin A-deficient rats.
abstract: Morphometric study revealed that, at 40 days after the start of vitamin A replacement, A1 spermatogonia and preleptotene spermatocytes appeared in more than 70% of the whole mounts of seminiferous tubules of vitamin A-deficient rats. By 42 days, the appearance of these cell types was reduced by 50%, and A2 and A3 spermatogonia were predominant. By 46 days, A1-A3 spermatogonia appeared in less than 30% of the tubular length while A4, intermediate and B spermatogonia became the major cell types in the basement compartment of seminiferous tubules. The predominance of spermatogonia noted at given times was corroborated by higher frequencies of tubular cross-sections of stages in which that particular type of spermatogonium resides. These results indicate that seminiferous tubules of vitamin A-replaced-vitamin A-deficient rats are 'enriched' for particular stages. Tracing the development of [3H]thymidine-labelled preleptotene spermatocytes revealed normal kinetics of germ cell differentiation in these animals. Furthermore, the spermatogonial proliferations in the vitamin A-replaced-vitamin A-deficient rats were quantitatively normal. We suggest that vitamin A replacement may result in temporal suppression of the differentiation of A2-B spermatogonia, leading to a stimulation or synchronization of certain groups of undifferentiating spermatogonia which undergo active proliferation simultaneously. These synchronized populations of spermatogonia continue to proliferate and differentiate, thus resulting in the stage-enrichments noted at later times.
authors.affiliation: Max Planck Clinical Research Unit for Reproductive Medicine, Munster, Federal Republic of Germany.
authors.forename: H F
authors.initials: HF
authors.lastname: Huang
authors.forename: G R
authors.initials: GR
authors.lastname: Marshall
authors.forename: E
authors.initials: E
authors.lastname: Nieschlag
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000502:physiology; D007700:Kinetics; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012670:Seminiferous Epithelium / Q000473:pathology / Q000502:physiology*; D013093:Spermatogonia / Q000166:cytology / Q000473:pathology / Q000502:physiology*; D013094:Spermatozoa / Q000502:physiology*; D013737:Testis / Q000502:physiology*; D014801:Vitamin A / Q000627:therapeutic use*; D014802:Vitamin A Deficiency / Q000188:drug therapy* / Q000473:pathology
chemical_list: D014801:Vitamin A