Morphological Tools for Describing the Male External Genitalia ofSapajus apella

Observations on the anatomy of the funiculus spermaticus and the testis in Brachyteles sp. (SPIX, 1823) primates - Atelidae

BACKGROUND

Analysing the literature about the reproductive anatomy on New World Primates, one can see the need of standardisation on the description methods and, more importantly, the lack of detailed information. The problem is aggravated by the difficult access to specimens of the endangered species such as Brachyteles sp. This paper's objective was to extend knowledge on the male reproductive anatomy of these primates. The testis and funiculus spermaticus of Brachyteles are described in detail.

METHODS

We utilised one individual of Brachyteles arachnoides, two hybrids (B. arachnoides × Brachyteles hypoxanthus) and photographs of the testis of a third fresh specimen of a hybrid individual.

RESULTS

The septum formed by tunica dartos adheres to the testis and separates the scrotum in two testicular cavities. Passed the spermatic cord, the external spermatic fascia continues with the tunica dartos, covering the cranial half of the testis. The fascia cremasterica divides itself in bundles of fibres and forms loops around the testicles creating a sac like structure that seems to be unique among Neotropical Primates. The appendix testis is described for the first time in platyrrhini. It is presented as a sessile structure in the extremitas capitata of the testis. Previous literature on the reproductive anatomy of platyrrhini is limited. Despite that, it can be said that the large size and volume of the testis, and complex structure of the cremaster, could consist of a heat loss reduction strategy in cold and humid forest environments.

CONCLUSIONS

Except for the larger size of the testicles in hybrid individuals, no other significant morphological differences were found between B. arachnoides and hybrids (B. arachnoides × B. hypoxanthus).

Male genital organs of the black-crowned dwarf marmoset (Callibella humilis)

This study provides the first morphological description of the male genital organs of black-crowned dwarf marmoset (Callibella humilis). Internal and external genital organs were similar to other species of non-human primates. However, some shape and size differences were noted. The penile shaft was laterally flattened and comprised of two corpus cavernosus. These were split by a septum up to the level of the glans and then merged to form a single structure. The glans penis had small, keratinized spicules arising from epidermal or dermal projections. The small, fully ossified and well-mineralized penile bone, located at the distal end of the penis, consisted of a bone matrix surrounded by sparse osteoblasts and well-developed internal osteocytes. The penile urethra was lined with columnar pseudostratified epithelium, with areas of simple cuboidal epithelium. The testes were small relative to the body compared to other primate species. The findings of this work may support comparative studies of primate reproductive ecology.

Gross anatomical description of the extrinsic and intrinsic scapular and brachial muscles of Sapajus apella (Linnaeus, 1758)

BACKGROUND

The robust brown capuchin monkey (Sapajus apella) is a South American primate with preferences for arboreal locomotion, which requires specific thoracic limb muscle adaptations. The present investigation studied the gross anatomy of the extrinsic and intrinsic scapular and brachial muscles.

METHODS

Gross dissections were performed in both thoracic limbs of four formaldehyde-fixed specimens.

RESULTS

Three rhomboideus muscles were present (capitis, cervicis, and thoracis). The trapezius muscle was divided into two parts (cervicis and thoracis). The pectoralis abdominalis and omotransversarius muscles were present. The anconeus muscle was found as an individual muscle or fused to the caput mediale of the triceps brachii muscle. The brachialis muscle had among one and two heads. The anconeus epitrochlearis was absent.

CONCLUSION

These muscles of Sapajus apella are adapted for arboreal locomotion and some terrestrial habits, since these have many similarities with other primates with a similar locomotor patterns.

Morphology of the male reproductive tract of Eira barbara

Eira barbara, popularly known as irara, is a medium-sized carnivore member of the Mustelidae family. Despite its important role in the ecosystems in which its lives, data on the internal morphology of E. barbara remains scarce. Therefore, this study aimed to provide knowledge regarding the anatomy of the male reproductive system of this species to improve understanding of its reproduction to inform its conservation. We studied seven specimens who had died after being run over. The specimens were dissected for the evaluation of the reproductive system, which comprised a globular scrotum; a small pendulum covered with light-coloured hair; a pair of testicles of firm consistency and ellipsoid shape and suspended in the scrotum by the spermatic cord; a paired duct system; an ampoule of the deferens duct and prostate constituting the set of attached glands; a urethra divided into pelvic and penile portions; a penis with a baculum having a novel "C" shaped apex; and a prepuce. Microscopically, the testicular parenchyma consisted of seminiferous tubules separated by intertubular spaces formed by loose connective tissue, fibrocytes, Leydig cells, and blood and lymph vessels. The epididymis was surrounded by a capsule of dense connective tissue and extended to form septa. The baculum was microscopically classified as a compact bone containing several bony lamellae with osteocytes and osteoblasts. The macro and microscopic findings were generally similar to those of domestic carnivores, with some notable differences.

Anatomy of the basal nuclei of Alouatta belzebul

Abstract The basal nuclei are well-defined bodies of neurons with specific functions, located inside the white medullary center of the brain, directly involved with the motor system, participating greatly in the planning and control processes of movements. Studies on these nuclei in non-human primates are small and in the Alouatta belzebul species, nonexistent. The aim of the present study was to describe the morphology of the nuclei at the base of the brain of Alouatta belzebul. Ten male and female Alouatta belzebul brains were used, where after removal and coronal cut of the brain, the Mayland technique was performed to show the basal nuclei. There was the presence of the caudate nucleus, lentiform nucleus (this formed by the putamen, medial globus pallidus and lateral globus pallidus), claustrum and substantia nigra, which, functionally, are related to motor control. The substantia nigra is part of the midbrain and is also related to learning resulting from the effects of dopamine, responsible for activating the reward and addiction system in the telbrain and is also related to the red nucleus, which is also a midbrain nucleus. In Alouatta belzebul the red nucleus is present. It was found in the literature that degeneration of substantia nigra cells can cause Parkinson's disease in Macaca fasciculares, and because Alouatta belzebul has the same anatomical structures in the basal nuclei of the base of Macaca fasciculares, it is suggested that studies of functional evaluation of these structures should be carried out to verify whether Alouatta belzebul can be used as an experimental model for Parkinson's disease.

Reproductive biology of owl (Aotus spp.) and capuchin (Sapajus spp.) monkeys

Studies related to morpho-physiology improve the understanding of biological mechanisms in non-human primates (NHP), contributing to research in several areas, especially those of assisted reproduction and biomedicine. The genera Aotus and Sapajus are important considerations in conducting studies related to reproductive biology and biomedical research, where animals of these genera can serve as models for species with vulnerable conservation status. The reproductive functions of animals of these genera can be used in conducting studies with other NHP species, for which biological material is difficult to access. The aim in conducting the current review was to compile the scientific literature on the biology and reproductive aspects of these two genera, to provide a for a greater understanding of these topics. In addition, a systematic review of literature allows for efficient access relevant information from an extended timeframe collated in a single document. There was, therefore, a systematic search for keywords based on reproductive studies with animals in these genera conducted, and 58 articles, 12 books, and three academic theses were subsequently selected. Even though there have been advances in knowledge of the reproductive biology of animals from these genera that have occurred in recent decades, especially research conducted when these NHP were in captivity, a wide variety of areas remain to be studied so that the understanding of reproduction in these NHP can be enhanced and the knowledge gained from these studies utilized for greater understanding of reproduction of NHP in general.

Clitoral length in immature and mature captive tufted capuchin (Sapajus spp.) females: A cross-sectional study

Quantitative data on female external genital morphology are sporadic in the primate literature, and the intraspecific and interfemale variation is especially under investigated (e.g., external clitoris length). Since in most anthropoid primate species female external genitals are relatively small and often hidden, for those species whose external clitoris is described as hypertrophic, external genital resemblance may represent a source of confusion in distinguishing the sexes at a distance. This is the case of both captive and wild tufted capuchin (Sapajus spp.) infants. We provided data on external clitoral length and investigated differences in this trait at different ages in a captive female tufted capuchin population. Since likely allometric growth describes changes in relative dimensions of parts of the body that are correlated with changes in overall size, clitoris length has been analyzed by using body weight as a covariate. We measured clitoral length by adapting a technique developed for spotted hyenas (Crocuta crocuta). Our results suggest that the small body size may be only in part responsible of the perception of long clitoris in female infants, since the clitoris is actually longer in immature females compared to adult ones and its size is inversely related to body weight. While the cross-sectional nature of these data does not allow for conclusive interpretation of the results, we tentatively suggest this phenomenon as a transient male-mimicry by immature females. Our study contributed to the description of normative data in a clitoral trait, thus providing foundation for future studies about causal mechanisms and possible adaptive function(s).

Morphological description of male genital organs of Marca's marmoset (Mico marcai)

Morphological characterisation of the genital organs of primates may bring significant contributions to the understanding of different reproductive behaviours and support new conservation strategies. However, relevant or detailed descriptions of genital morphology of several primate species are still lacking. This study describes the gross and microscopic anatomy of the internal and external genitalia of Marca's marmoset (Mico marcai). The same organs described in other primate species were identified here, but some anatomical particularities were detected, such as absence of a dartos tunic, presence of a vas deferens ampulla, absence of spongious erectile tissue in the pelvic urethra, separation of prostate gland lobes by a longitudinal sulcus and lack of septation in the corpus cavernosus and spongiosus at the level of the shaft and free portion of the penis. Keratinised type 1 spicules arising from epidermal or dermal projections were found in the free portion of the penis. Microscopic analysis revealed a small bone (baculum) consisting of peripheral compact bone and a central, non-ossified area filled with vascular tissue at the distal end of this portion of the penis. Results of this study may support further comparative studies of primates' reproductive ecology.

Anatomia e histologia do trato urinário do macaco-prego (Sapajus apella)

Resumo: Sapajus apella é um primata do Novo Mundo de porte médio e com distribuição geográfica desde a América do Sul até a Argentina. São bons modelos para estudo e nos últimos anos vêm sendo amplamente utilizados para este fim. A destruição progressiva do habitat natural desses animais os tem levado a migrarem para outras regiões, tornando-os, assim, mais susceptíveis à caça predatória. A necessidade de preservação das espécies silvestres desperta interesse por um maior conhecimento anatômico e clínico para estes animais. O presente estudo teve como objetivo examinar e descrever os aspectos morfológicos, quanto a anatomia macroscópica e microscópica dos órgãos do sistema urinário de fêmeas da espécie Sapajus apella visando estender o conhecimento anatômico para esta espécie. Foram utilizadas quatro fêmeas, oriundas do Centro Nacional de Primatas de Ananindeua/PA. istema urinário de S. apella apresenta características similares a outros primatas tanto humanos quanto não humanos e aos animais domésticos. Os rins apresentaram aspectos macroscópicos semelhantes aos rins de humanos, mas com a mesma classificação de outros primatas não humanos e alguns animais domésticos. A bexiga assemelhou-se aos animais domésticos e aos primatas de maneira geral, humano e não humano. O mesmo ocorreu quando analisamos estes órgãos histologicamente.