Reproductive morphology of female Guiana dolphins (Sotalia guianensis).

Maria Angelica Miglino,Estella Z Becegato,Jociery E Vergara-Parente,Janaina P Andrade,Fernanda M De Oliveira E Silva,Juliana P Guimarães

doi:10.1590/0001-3765201520140432

Abstract

The reproductive morphology of cetaceans is poorly studied and, despite the large number of strandings, reports on this subject are scarce due to access to carcasses mostly in an advanced state of decomposition. The present study aimed to describe histological characteristics of the female genital tract of Sotalia guianensis, in order to assist in future studies on the reproductive biology of these animals. Females of different ages, from stranding events on beaches in northeastern Brazil, were used. Fragments of all organs were collected and processed for light and scanning electron microscopy. Histological analyses showed that these structures were similar to those found in terrestrial mammals, with some peculiarities, such as the presence of differentiated cells in the vulvar subepidermal layer, not described in the literature on cetaceans. Reproductive studies with a morphological description of the female genital organs are extremely important, since they would enable a better understanding of the species reproductive physiology and assist in the development of new strategies for the species conservation.

Highlights

The order Cetacea includes whales, dolphins and porpoises (Berta et al 2006), animals with distinct characteristics such as reproductive seasonality, polygamous behavior (Schaeff 2007) and a relatively long estrous cycle when compared to terrestrial mammals (Boness 2009).The reproductive period is related to the seasonality for some cetacean species, such as Sotalia fluviatilis (Best and Da Silva 1984) and occur as a discrete phase together with other aspects such as the presence of food, which differs from Sotalia guianensis
Some anatomical and reproductive aspects of cetaceans have been studied through macroscopic analysis (Ramos et al 2000, Best and Da Silva 1984) and have determined the reproductive maturity in females by the presence of corpus albicans, a structure used to measure the number of ovulations since they persist for a lifetime in the ovary in most cetacean species (Berta and Sumich 1999)
Studies reporting the microscopic anatomy of the female genital organs are scarce

Summary

Introduction

The order Cetacea includes whales, dolphins and porpoises (Berta et al 2006), animals with distinct characteristics such as reproductive seasonality, polygamous behavior (Schaeff 2007) and a relatively long estrous cycle when compared to terrestrial mammals (Boness 2009).The reproductive period is related to the seasonality for some cetacean species, such as Sotalia fluviatilis (Best and Da Silva 1984) and occur as a discrete phase together with other aspects such as the presence of food, which differs from Sotalia guianensis. The polygamous behavior derives from the long period of calf caring conferred exclusively to females. In some species such as Tursiops truncatus, sequential polygamy occurs, i.e. during the breeding season males are associated with a female for a short time, leave to find another receptive female (Schaeff 2007). Some anatomical and reproductive aspects of cetaceans have been studied through macroscopic analysis (Ramos et al 2000, Best and Da Silva 1984) and have determined the reproductive maturity in females by the presence of corpus albicans, a structure used to measure the number of ovulations since they persist for a lifetime in the ovary in most cetacean species (Berta and Sumich 1999). Studies reporting the microscopic anatomy of the female genital organs are scarce

Methods

Results

Conclusion