Lectin histochemical study of vasculogenesis during rat pituitary morphogenesis

The aim of this study was to investigate glycoconjugates distribution patterns as well as their changes during the course of pituitary portal vasculogenesis and angiogenesis. Formalin fixed paraffin sections of 10 to 20 days of Sprague Dawly rat fetuses were processed for histochemical studies using four different horseradish peroxidase [HRP] conjugated lectins. Orange peel fungus [OFA], Vicica villosa [VVA], Glycine max [SBA] and Wistaria floribunda [WFA] specific for alpha-L-Fucose, D-Gal, alpha, beta-D-GalNAc and D-GalNAc terminal sugars of glycoconjugates respectively. Our finding indicated that adenohypophysal cells reacted with OFA on gestational day 10 E[10] and increased progressively to E[14]. Staining intensity did not change from days 14 to17, then after increased following days to E[20] significantly [P< 0.05]. A few cells around Rathke's pouch reacted with VVA on E[13], increased to E[14] and decreased significantly afterward [P< 0.05]. Reaction of some cells around Rathke's pouch reacted with SBA on E[14]. This visible reaction was the same as E[18] and decreased later [P< 0.05]. Many cells around Rathke's pouch reacted with WFA on E[13] and increased on E[14] and E[15] and decreased thereafter [P<0.05]. Reactions of OFA and other tested lectins with endothelial cells around Rathke's pouch and developing pars distalis were different. These results suggest that embryonic origin of hypophiseal pituitary portal [HPP] system endothelial cells are not the same and our finding also indicated that glycoconjugates with terminal sugars alpha-L-Fucose, D-Gal, alpha, beta-D-GalNAc may play critical role[s] in cell interactions and tissue differentiations such as vasculogensis and angiogenesis as well as other developmental precursors in formation of the pituitary gland

Effect of tyrosine on the pars distalis of the rabbits hypothesis

The present study was conducted on 36 Newzeal and white rabbits assigned into three age groups of 2, 3 and 4 months, 12 rabbits for each group of the same age [6 males and 6 females]. For each sex, 4 rabbits were given orally a single dose of L-tyrosine, 100 mg/kg body weight and the other two rabbits, were left as control. The treated groups revealed an increase in the amount, size and the secretory activity of somatotrophs, lactotrophs and LH gonadotrophs, in addition to a marked increase in the amount, size and the secretory activity of thyrotrophs, adrenocorticotrophs and FSH gonadotrophs during the second month of age. From the present results it could be concluded that tyrosine acts as a growth promoting factor and a hormonal inducing factor, it can be used in rabbits for enhancing the puberty of both males and females. It could be recommended that tyrosine can be used on a large scale for regulating the reproductive cycle of males and females in large animals