Stereological comparison of smooth muscle, collagen, and elastic fibers of the clitoris and glans penis in young adults

OBJECTIVE

To compare the collagen, elastic fibers, and smooth muscle content of the clitoris and the glans penis in young adults.

MATERIALS AND METHODS

The clitoris and the glans penis of six women and six men (mean age 25±3) who died as a result of accidents were excised. The samples were placed under a formaldehyde solution and histologically processed. Masson's trichrome and Weigert's resorcin-fuchsin stain was used to highlight the elastic fibers, smooth muscle, and collagen. Stereological analysis was conducted in 5 random fields of 5 slides for each sample. For statistical analysis, the unpaired t-test was used to compare values between groups, and a value of P<0.05 was considered as significant for all analyses.

RESULTS

Stereology revealed a mean smooth muscle content of 35.84±6.46% and 31.64±4.74% for the clitoris and glans penis, respectively, while it also revealed collagen content of 26.11±7.41% and 28.44±3.55% and elastic fibers content of 24.12±4.34% and 30.97±6.13% for the clitoris and glans penis, respectively. The statistical analysis showed no significant differences between them.

CONCLUSION

Regardless of anatomical differences, the volumetric density of collagen, elastic fibers, and smooth muscle were similar for the clitoris and glans penis in young adults, a feature possibly explained by their embryology.

Transmucosal oxygen tension of the clitoris: a new parameter for future investigations of the sexual, metabolic, and cardiovascular health of women

BACKGROUND

Several studies suggested that abnormalities in tissue perfusion of external genitalia and vagina can lead to female sexual dysfunctions (FSDs) and can be associated to metabolic and cardiovascular risk factors. However, there are some technical difficulties in assessing these abnormalities. The measurement of oxygen partial pressure is a noninvasive method to measure oxygen partial pressure (pO₂) at the skin surface to assess tissue perfusion. The aim of this study was to evaluate whether transmucosal oxygen tension (TmPO₂) can be measured at the mucosal surface of clitoris and whether the measurements are reliable.

METHODS

TmPO₂ was measured in six young healthy women by using a device to measure transcutaneous pO₂ on the skin and by choosing a small sensor, usually used for newborns. The identical procedure for the detection of pO₂ at the skin surface was used.

RESULTS

The mean value of TmPO₂ was 42.3 mmHg (range: 24.1-53.4 mmHg). All the trend curves of the TmPO₂ showed the same behavior: after a stabilization time, there was a stable pO₂ (plateau phase) that corresponds to the TmPO₂ of the clitoris. These curves had a similar trend to those recorded at the skin surface.

CONCLUSIONS

TmPO₂ can be easily measured at the mucosal surface of clitoris. Large epidemiological studies in healthy and unhealthy women and in women with FSD are needed to establish both the normal range of TmPO₂ and the meaning that different values of TmPO₂ can have on sexual and general health of the women.

Immunohistochemical characteristics of the nerve fibres of sow retractor clitoridis muscle

The occurrence of several biologically active neuropeptides (calcitonine gene-related peptide, leu-enkephaline, neuropeptide Y, substance P, and vasoactive intestinal peptide) or nitric oxide-synthesizing enzymes (neuronal nitric oxide synthase), tyrosine hydroxylase, vesicular acetylcholine transporter, and their co-localization with tyrosine hydroxylase were investigated by immunohistochemistry in the retractor clitoridis muscle of slaughtered sows. Single immunolabelling revealed that tyrosine hydroxylase and neuropeptide Y immunoreactive nerve fibres were the most numerous, followed by the neuronal nitric oxide synthase and calcitonine gene-related peptide immunoreactive ones, the vasoactive intestinal peptide, substance P and leu-enkephaline immunoreactive nerve fibres were few and vesicular acetylcholine transporter immunoreactivity were observed only in single fibres. Double immunolabelling revealed the only co-localization of tyrosyne hydroxylase with neuropeptide Y. The most reliable labelling of nerve fibres of the retractor clitoridis muscle was observed around blood vessels, followed by non-vascular smooth muscles. The present data indicate that the sow retractor clitoridis muscle receives nerve fibres that exhibit different chemical codes and, likely, differences in their chemical coding depend on the target-structure.

Identification of sex-associated protein in the preputial gland of house rat (a new insight in rodent pest management)

Our recent findings revealed that the preputial gland of male house rat contains 20 kDa protein, however, the role of androgen in the production of this protein is not known. Hence, the present study was carried out to evaluate the androgen dependency of 20 kDa protein in the preputial gland of house rat (Rattus rattus) and to compare its presence in female clitoral gland. Further, on castration the amount of glandular protein in male was significantly decreased to a certain extent, while testosterone treatment on castrated males showed an increasing trend. The electrophorogram of male house rat showed six different protein fractions with molecular weights of 90, 70, 60, 50, 35 and 20 kDa. However, the 70, 60, 50 and 35 kDa were absent in female. Among the different fractions, 90 and 20 kDa proteins were prominent. On castration, the 20 kDa protein was disappeared; while on testosterone treatment the protein reappeared. Thus, the present study concludes that the 20 kDa protein is a testosterone dependent sex-associated protein. Since urinary protein is found to act as carrier for volatile substances in pheromonal communication. The present study suggests that the glandular protein may bind with the volatile compounds produced from preputial gland. Identification of this carrier protein in the preputial gland explores the possibility of developing pheromonal trap for rodent pest management (RPM).

Renin angiotensin system of rabbit clitoral cavernosum: interaction with nitric oxide

PURPOSE

Angiotensin (ANG) II has been known to be a potent modulator for the maintenance of smooth muscle tone of the penile cavernosum. However, its role in clitoral cavernosum is unknown. The clitoris is the homologue of the penis arising from the embryological genital tubercle. We investigated the presence of ANG II receptors, the function of ANG II, and its interaction with nitric oxide (NO) in rabbit clitoral cavernosum.

MATERIALS AND METHODS

The isometric tension was measured in the strips of clitoral cavernosum. Reverse transcriptase polymerase chain reaction (RT-PCR) was used to evaluate expression of AT1a and AT1b ANG II receptor subtype mRNAs. In vitro autoradiography was used to localize ANG II receptors in the clitoral cavernosum.

RESULTS

The clitoral cavernosum was contracted dose-dependently by the addition of ANG II. Dup 753 (ANG II type 1 receptor antagonist) inhibited significantly ANG II induced contraction. PD 123,319 (ANG II type 2 receptor antagonist) did not affect the ANG II response. Pretreatment with NG-nitro-L-arginine methyl ester (NO synthase inhibitor) accentuated contractions induced by ANG II. Specific binding sites for 125I-ANG II were found in the clitoral cavernosum. The dissociation constant (Kd) was 0.58 + or - 0.05 nM. Specific binding of 125I-ANG II was displaced by Dup 753 (10-5 M) but not by PD 123,319 (10-5 M). The inhibitory constant (Ki) for Dup 753 was 23. 4 + or - 9.73 nM and mRNAs for AT1a and AT1b receptor subtypes were detected by RT-PCR.

CONCLUSION

The present study shows that ANG II is involved in the regulation of clitoral cavernosum smooth muscle tone via ANG II receptor subtype AT1, and that ANG II has cross-talk with NO.

Immunohistochemical description of nitric oxide synthase isoforms in human clitoris

PURPOSE

Our aim was to identify and localize nitric oxide synthase isoforms in the human clitoris in support of the hypothesis that nitric oxide mediates erectile function in this organ.

MATERIALS AND METHODS

Nitric oxide synthase immunohistochemistry studies specific for neuronal, inducible and endothelial isoforms of the enzyme were performed on human clitoral tissue obtained from 4 patients (3 with female pseudohermaphroditism and 1 with true hermaphroditism) at feminizing genitoplasty and from 1 phenotypically normal woman at autopsy.

RESULTS

Neuronal nitric oxide synthase immunoreactivity was detected in nerve bundles and fibers coursing within the glans clitoris and corpora cavernosa of the clitoris, predominating in the latter tissue. Specific inducible nitric oxide synthase immunoreactivity was not identified. Endothelial nitric oxide synthase immunoreactivity was detected in vascular and sinusoidal endothelium of these tissues with a predominance in the glans clitoris.

CONCLUSIONS

The presence and anatomical localizations of nitric oxide synthase isoforms in the human clitoris indicate that nitric oxide is generated in this organ. These data suggest that nitric oxide may be involved in the erectile physiology of the clitoris as a modulator of clitoral smooth muscle activity. Functional studies are required to support this hypothesis.

Immunohistochemical study of the corpora cavernosa of the human clitoris

The microarchitecture of the corpora cavernosa of the human clitoris was investigated by immunohistochemistry. The distribution pattern of the nerve network was demonstrated by S-100 and neuron specific enolase immunoreactivity. Vascular and nonvascular muscle cells were identified by desmin and/or vimentin expression, and fibroblasts and endothelial cells by vimentin immunoreactivity. The findings show that tissue organisation in the corpora cavernosa of the clitoris is essentially similar to that of the penis except for the absence of the subalbugineal layer interposed between the tunica albuginea and erectile tissue. This has functional implications, suggesting that the clitoral erection cycle differs from that of the penis.

Immunohistochemical study of neuropeptide Y-containing nerve fibers in the human clitoris and penis

The occurrence and distribution of neuropeptide Y in the human clitoris and penis was investigated by light immunohistochemistry. Neuropeptide Y-containing nerve fibers were detected in the tunicae of arteries and veins as well as among trabecular smooth muscle. The distribution pattern of the peptide was similar in both organs although a higher density of immunoreactive nerve fibers was detected in the penis. The immunolocalization of neuropeptide Y was also compared with that of neuron-specific enolase, a neuronal marker which labels the entire nerve network. It is suggested that neuropeptide Y is involved in the physiology of the penis and the clitoris, affecting vascular and nonvascular smooth muscle activity.