The Evolutionary Implications of Hemipenial Morphology of Rattlesnake Crotalus durissus terrificus (Laurent, 1768) (Serpentes: Viperidae: Crotalinae).

Most amniotes vertebrates have an intromittent organ to deliver semen. The reptile Sphenodon and most birds lost the ancestral penis and developed a cloaca-cloaca mating. Known as hemipenises, the copulatory organ of Squamata shows unique features between the amniotes intromittent organ. They are the only paired intromittent organs across amniotes and are fully inverted and encapsulated in the tail when not in use. The histology and ultrastructure of the hemipenes of Crotalus durissus rattlesnake is described as the evolutionary implications of the main features discussed. The organization of hemipenis of Crotalus durissus terrificus in two concentric corpora cavernosa is similar to other Squamata but differ markedly from the organization of the penis found in crocodilians, testudinata, birds and mammals. Based on the available data, the penis of the ancestral amniotes was made of connective tissue and the incorporation of smooth muscle in the framework of the sinusoids occurred independently in mammals and Crotalus durissus. The propulsor action of the muscle retractor penis basalis was confirmed and therefore the named should be changed to musculus hemipenis propulsor.The retractor penis magnus found in Squamata has no homology to the retractor penis of mammals, although both are responsible for the retraction of the copulatory organ.

Role of a novel tetrodotoxin-resistant sodium channel in the nitrergic relaxation of corpus cavernosum from the South American rattlesnake Crotalus durissus terrificus.

INTRODUCTION: Coitus in snakes may last up to 28 hours; however, the mechanisms involved are unknown. AIM: To evaluate the relevance of the nitric oxide (NO)-cyclic guanosine monophosphate (cGMP)-phosphodiesterase type 5 (PDE5) system in snake corpus cavernosum reactivity. METHODS: Hemipenes were removed from anesthetized South American rattlesnakes (Crotalus durissus terrificus) and studied by light and scanning electronic microscopy. Isolated Crotalus corpora cavernosa (CCC) were dissected from the non-spiny region of the hemipenises, and tissue reactivity was assessed in organ baths. MAIN OUTCOME MEASURES: Cumulative concentration-response curves were constructed for acetylcholine (ACh), sodium nitroprusside (SNP), 5-cyclopropyl-2-[1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridine-3-yl]pyrimidin-4-ylamine (BAY 41-2272), and tadalafil in CCC precontracted with phenylephrine. Relaxation induced by electrical field stimulation (EFS) was also done in the absence and presence of N(ω) nitro-L-arginine methyl ester (L-NAME; 100 µM), 1H-[1, 2, 4] oxadiazolo[4,3-a]quinoxalin-1-one (ODQ; 10 µM) and tetrodotoxin (TTX; 1 µM). RESULTS: The hemipenes consisted of two functionally concentric corpora cavernosa, one of them containing radiating bundles of smooth muscle fibers (confirmed by α-actin immunostaining). Endothelial and neural nitric oxide synthases were present in the endothelium and neural structures, respectively; whereas soluble guanylate cyclase and PDE5 were expressed in trabecular smooth muscle. ACh and SNP relaxed isolated CCC, with the relaxations being markedly reduced by L-NAME and ODQ, respectively. BAY 41-2272 and tadalafil caused sustained relaxations with potency (pEC(50) ) values of 5.84 ± 0.17 and 5.10 ± 0.08 (N=3-4), respectively. In precontracted CCC, EFS caused frequency-dependent relaxations that lasted three times longer than those in mammalian CC. Although these relaxations were almost abolished by either L-NAME or ODQ, they were unaffected by TTX. In contrast, EFS-induced relaxations in marmoset CC were abolished by TTX. CONCLUSIONS: Rattlesnake CC relaxation is mediated by the NO-cGMP-PDE5 pathway in a manner similar to mammals. The novel TTX-resistant Na channel identified here may be responsible for the slow response of smooth muscle following nerve stimulation and could explain the extraordinary duration of snake coitus.

Impotência vasculogênica: contribuiçöes ao estudo do fator venoso / Vasculogenic impotence: contribution to the study of the venous factor

Os pacientes portadores de varicocele e inadequaçäo sexual parecem se distribuir em duas subpopulaçöes distintas. A primeira tem como principal manifestaçäo clínica a baixa de libido e, a segunda, como manifestaçäo básica, os distúrbios de ereçäo, associados ou näo a alteraçöes da libido. Foi possível verificar que a subpopulaçäo portadora de baixa libido apresenta nítida depressäo da funçäo androgênica testicular. Ao contrário, em pacientes com disfunçöes eréteis mas libido normal, näo foram verificadas alteraçöes do perfil androgênico. O achados de níveis hormonais normais nos casos de disfunçäo erétil pura parece sugerir a existência de mecanismo fisiopatológico outro, näo-hormonal, que pudesse explicá-la. As alteraçöes do plateau e do ramo descendente da curva de fluxo sangüíneo peniano com hemácias autólogas marcadas constituem evidências de alteraçöes patológicas do sistema de drenagem venosa do pênis. Da mesma forma, os achados de cavernosogramas seriados anormais em alguns dos pacientes com disfunçäo erétil pura e varicocele é sugestivo de alteraçöes de drenagem venosa peniana. O estudo histopatológico de biópsias da veia dorsal profunda do pênis, em casos de disfunçäo erétil pura associada a varicocele, revelou a existência de lesöes típicas de flebectasia desse vaso. Tais evidências, em conjunto, levam o autor a propor dois mecanismos fisiopatológicos distintos nas inadequaçöes sexuais associadas à varicocele: as alteraçöes hormonais seriam responsáveis diretas apenas pela baixa de libido, enquanto que as disfunçöes eréteis seriam explicadas pelas lesöes vasculares do sistema de drenagem venosa do próprio pênis. Esses achados ampliam os conceitos vigentes na literatura, deságuam no primeiro estudo histopatológico sistemático de veias penianas na impotência erétil vasculogênica e, principalmente, conduzem à proposiçäo original da concomitância de lesöes venosas penianas e testiculares. A monografia chega a seu objetivo final: a proposiçäo de uma síndrome de venopatia genital