Abou-Easa K, El-Magd MA, Tousson E, Amin Hassanin, Shukry M, Salama M
الملخص العربي
Several functional and morphological studies have been conducted on the pineal gland in many mammalian
species; however, no published reports are available on the role of pineal gland on the gonadal development before and after eyelids
separation in puppies. Therefore, this study aimed to trace the postnatal histo-morphological changes in the pineal gland and gonads of
puppies before (2, 10 and 11 days old) and after (25, 35 and 40 days old) eyelids separation in an attempt to investigate the possible role
of pineal gland on the gonadal development. In general, the differentiation of pineal cells, interstitial endocrine cells of testes and stromal
ovarian cells coincides with the start of eyelids separation in puppies. Histological examination of stained pineal and gonadal slices of
puppies after eyelids separation revealed a remarkable differentiation of pinealocytes and testicular interstitial endocrine cells, as well as
presence of some evidence of folliculogenesis in ovary. Surprisingly, melatonin receptor (MT1) protein expression levels were significantly
increased in the ovaries and testes of puppies after eyelids separation. Moreover, the mRNA and protein expression of AANAT, a ratelimiting
enzyme in melatonin biosynthesis, was notably increased in the pineal gland of opened eyes puppies. Our results suggest an
increase of melatonin production from the pineal gland of opened eyes puppies and this could play a vital role in the developmental
changes observed in the gonads of these puppies.
محمد رزق ابو المجد الغنام | Mohammed Rizk Abu El-Magd El-Ghannam | 8923