Histomorphology of preorbital gland in territorial and non-territorial male blackbuck Antelope cervicapra, a critically endangered species

Abstract

Abstract:The preorbital gland is a specialized dermal gland of antelopes which plays an important role in territorial marking behavior and pheromonal communication. To our knowledge, there is little information available on the role of preorbital gland marks in Indian antelopes (blackbucks). Males are seen averting the gland during behavioural display and territorial marking but the functional aspect of this gland has not been examined. Hence, the aim of this study was to describe the histomorphology of the preorbital gland in territorial and non-territorial male blackbucks to determine its morphology and secretory function. The results showed that the preorbital gland is composed of modified sebaceous and apocrine glands. The apocrine gland is lined by simple cuboidal epithelial cells; the serous parts of the secretory products are often seen in the apical portions of the cells. The myoepithelial cells contain actin filaments lying on the basal membranes of the apocrine gland. There are some considerable histological changes in the presence of the sebaceous and apocrine glands in territorial males in comparison to non-territorial males. The following histological changes associated with occurrence of the sebaceous and apocrine glands have been observed in territorial and non-territorial male blackbucks: (1) increase of size of sebaceous and apocrine glands and (2) increase in density of sebaceous and apocrine glands in territorial males compared to non-territorial males. It is suggested that the higher development (i.e., size) and density of sebaceous and apocrine glands in territorial males could depend on hormone production (i.e., testosterone). Based on the histological observation and the role of sebaceous and apocrine glands in the preorbital gland supported by literature, it is possible to conclude that both territorial and non-territorial blackbuck males may produce pheromonal substances through preorbital gland (secretion) for olfactory communication.

Histomorphological perspectives of preputial and clitoral glands of soft-furred field rat Millardia meltada

“…The significant difference of the morphometric parameters (i.e., length, width, and weight) between preputial and clitoral glands is to be perceived as manifestation of the sexual difference of the pheromone secreting glands between male and female soft-furred field rat which is in agreement with the condition in Iranian sheep (Abbasi et al 2009), Egyptian sheep (Awaad et al 2015), Awassi sheep (Yilmaz et al 2017), and Bandicoot rat (Ponmanickam et al 2016). In another context, the preorbital gland length, width and weight were higher in dominant male (i.e., adult) than subordinate male (i.e., sub-adult and adolescent) blackbucks (Rajagopal and Archunan 2011). According to Zhang et al (2008) the scent glands of rats do not exhibit sexual differences, but gonadectomy resulted in significant decrease of size of the scent glands of both sexes.…”

“…This is a clear histomorphological manifestation of sexual dimorphism. Similar findings have been made on intermandibular glands of lesser mouse deer (Agungpriyono et al 2006), infraorbital gland of the barking deer (Adnyane et al 2011) and preorbital gland of the blackbuck (Rajagopal and Archunan 2011), but the finding contradicts the observation made on infraorbital glands of the Japanese serow (Atoji et al 1987), and Formosan serow (Atoji et al 1996) and interdigital glands of sheep (Misk and Misk 2013). According to Zhang et al (2008) rat male scent gland secretion is rich in squalene compared to female gland, whereas farnesol content was lower in male scent gland than female gland.…”

“…The preputial and clitoral glands were removed carefully, and the rats were sacrificed under excess ketamine (2 mg/kg, iv). The length and width of the glands were measured using a graph sheet, and then weighed in a monopan balance (Rajagopal and Archunan 2011).…”

Localization of α 2u-globulin in the acinar cells of preputial gland, and confirmation of its binding with farnesol, a putative pheromone, in field rat (Millardia meltada)

“…We found the cells adjacent to the core of the alveoli of the sebaceous gland to be filled with fat residues. The preorbital gland of dominant male blackbuck has both sebaceous and apocrine secretory glands [ 32 ]. The modified sebaceous glands in the scent glands of several antelopes have been reported [ 33 – 37 ].…”

“…They are also sex attractants [ 7 ]. During scent marking, the scent produced by the sebaceous gland is adhesive and lasts longer [ 30 , 32 , 42 ]. Also, in rodents there are possibilities that the secretions can be smeared on the path the animal travels to serve as scent marks for their conspecifics to recognise [ 43 ].…”