Introduction: The localization and characterization of the hypophyseal cell types in L. ramada is so far lacking.
Aim of the Work: The present study aimed to describe and determine the hypophyseal cells in L. ramada.
Material and Methods: Immunohistochemical localization of the hormone-secreting cells in the hypophysis of L. ramada was completed by antisera against both mammalian and piscine hormones.
Results: The hypophysis of L. ramada was comprised two main parts, the glandular part (adenohypophysis) and the nervous part (neurohypophysis). The adenohypophysis was divided into three subdivisions; rostral pars distalis (RPD), proximal pars distalis (PPD) and pars intermedia (PI). Seven of hormone-secreting cells were distinguished in the glandular part according to their grouping, distribution, and immunoreactivity.
The acidophilic prolactin (PRL) cells occupied the bulk of the RPD and showed positive and specific immunoreaction with salmon PRL antiserum. Lead hematoxylin-positive (PbH+) cells, which were bordered the neurohypophysis in the RPD, gave positive immunoreactivity with human adrenocorticotrophic (ACTH) antiserum.
The acidophilic cells of the PPD immunoreacted positively and strongly with antiserum against salmon growth hormone (GH). In addition, the central region of PPD comprised basophilic cells which were showed specific and strong immunoreaction with antisera against salmon gonadotropin (GTH) subunits; Iβ and IIβ.
The presumptive thyrotropin (TSH) secreting cells were distinguished in the neurohypophysis between the RPD and the PPD, and they were negative immunoreacted with antiserum against rat thyrotropin (rBetaTSH).
Two cell types were found in the PI; the Periodic Acid-Schiff-positive (PAS+) cells which had positive immunoreaction with anti-salmon somatolactin (SL) and the Lead hematoxylin-positive (PbH+) cells which immunostained with anti-alpha-melanin-stimulating hormone (α-MSH).
Conclusion: The localization of hypophyseal cells of L. ramada, consider as basis for understanding and tracking hormonal changes during its reproductive cycle in captivity.