Dissertação
Comparação morfofuncional entre a espermatogênese e a biologia espermatogonial de dois primatas: homem e sagui
Fecha
2017-08-29Autor
André Lucas Caldeira Brant de Oliveira
Institución
Resumen
Scientific studies that evaluate testicular function in human under healthy, pathological or
experimental conditions often use rodents as experimental models to verify the effects of
those conditions on the human testis. Currently, the New World monkeys, especially the
genus Callithrix sp, have been widely used in biomedical researches to evaluate testicular
biology as a preliminary test in non-human primates. However, despite being phylogeneticaly
related to humans, no studies have confidently described if the spermatogenic process
between these two species are comparable. Having said that, the objective of the present
study was to compare the spermatogenesis morphological and functional parameters’
between the human and the marmoset to further determine if such species could be an
adequate experimental model. To do so, testicular samples from four men and five marmosets
were processed according to high resolution light microscopy protocols. After the adaptation
of the marmoset seminiferous epithelium cycle from nine to six stages, it was observed that,
despite having an additional spermatogonial generation, the morphology of marmoset
spermatogonia was similar to the human’s ones. In terms of the spermatogenic process, it was
observed that the cellular associations present in the six stages of the SEC, their frequencies
and one of the spermatogenesis index (meiotic) were similar between both primates’ species.
In addition, it was noticed that Adark undifferentiated spermatogonia from both species
presented two subtypes: one with nuclear vacuole and another without such structure. Those
Adark with a nuclear vacuole were positioned in specific regions nearby blood vessels,
suggesting for the first time the presence of a spermatogonial niche in humans. The few
morphometric parameters that differed between man and marmoset were due to the
different number of spermatogonial generations (Adark, Apale and B in man; and Adark, Apale, B1
and B2 in the marmoset), which does not prevent the comparison between both species.
Considering the similarity between the spermatogenesis and spermatogonial biology of both
primates, we demonstrated that the marmoset can be used as a more adequate experimental
model in studies that aimed to understand the human testicular biology.