Robert J. Plenter

ANATOMICAL RELATIONSHIP BETWEEN URETHRA AND CLITORIS

PURPOSE We investigated the anatomical relationship between the urethra and the surrounding erectile tissue, and reviewed the appropriateness of the current nomenclature used to describe this anatomy. MATERIALS AND METHODS A detailed dissection was performed on 2 fresh and 8 fixed human female adult cadavers (age range 22 to 88 years). The relationship of the urethra to the surrounding erectile tissue was ascertained in each specimen, and the erectile tissue arrangement was determined and compared to standard anatomical descriptions. Nerves supplying the erectile tissue were carefully preserved and their relationship to the soft tissues and bony pelvis was noted. RESULTS The female urethra, distal vaginal wall and erectile tissue are packed into the perineum caudal (superficial) to the pubic arch, which is bounded laterally by the ischiopubic rami, and superficially by the labia minora and majora. This complex is not flat against the rami as is commonly depicted but projects from the bony landmarks for 3 to 6 cm. The perineal urethra is embedded in the anterior vaginal wall and is surrounded by erectile tissue in all directions except posteriorly where it relates to the vaginal wall. The bulbs of the vestibule are inappropriately named as they directly relate to the other clitoral components and the urethra. Their association with the vestibule is inconsistent and, thus, we recommend that these structures be renamed the bulbs of the clitoris. CONCLUSIONS A series of detailed dissections suggest that current anatomical descriptions of female human urethral and genital anatomy are inaccurate.

The suspensory ligament of the clitoris: Connective tissue supports of the erectile tissues of the female urogenital region

We aimed to define the gross anatomy of the supporting structures of the clitoris. We performed a dissection of the perineum of a series of 22 female and four male cadavers. Specific dissection of the clitoral and penile suspensory ligament complex was performed in four female and two male cadavers. Serial written observations and photography were used to document the findings. Our findings were then compared with the anatomical description of these structures in the historical and current anatomical literature. The suspensory ligament of clitoris consistently displayed two components: a superficial fibro‐fatty structure extending from a broad base within the mons pubis to converge on the body of the clitoris and extending into the labia majora; in addition there is a deep component with a narrow origin on the symphysis pubis extending to the body and the bulbs of the clitoris. The supporting structures of the clitoris are more substantial and complex than previously described. Their shape, extent, and orientation are different from analogous structures of the penis, the suspensory ligament of which was found as described in the literature. Clin. Anat. 13:397–403, 2000.

Acute cardiac allograft rejection by directly cytotoxic CD4 T cells: parallel requirements for Fas and perforin.

Background. CD4 T cells can suffice as effector cells to mediate primary acute cardiac allograft rejection. Although CD4 T cells can readily kill appropriate target cells in vitro, the corresponding role of such cytolytic activity for mediating allograft rejection in vivo is unknown. Therefore, we determined whether the cytolytic effector molecules perforin (PFP) and/or FasL (CD95L) were necessary for CD4 T cell-mediated rejection in vivo. Methods. Wild-type C3H(H-2k) or Fas (CD95)-deficient C3Hlpr (H-2k) hearts were transplanted into immune-deficient C57B6rag−/− (H-2b) mice. Then, recipients were reconstituted with naïve purified CD4 T cells from wild-type, PFP-deficient, or FasL (gld)-deficient T-cell donors. Results. In vitro, alloreactive CD4 T cells were competent to lyse donor major histocompatibility complex class II+ target cells, largely by a Fas-dependent mechanism. In vivo, the individual disruption of donor Fas expression (lpr) or CD4 T-cell-derived PFP had no significant impact on acute rejection. However, FasL-deficient (gld) CD4 T cells demonstrated delayed allograft rejection. Importantly, the simultaneous removal of both donor Fas expression and CD4 T-cell PFP completely abrogated acute rejection, despite the persistence of CD4 T cells within the graft. Conclusions. Results demonstrate that the direct rejection of cardiac allografts by CD4 effector T cells requires the alternative contribution of graft Fas expression and T cell PFP expression. To our knowledge, this is the first demonstration that cytolytic activity by CD4 T cells can play an obligate role for primary acute allograft rejection in vivo.

Four Decades of Vascularized Heterotopic Cardiac Transplantation in the Mouse

ABSTRACT Since the first clinical heart transplant in 1967, there has been a heightened need to understand immune and inflammatory responses to “foreign” tissues. Research efforts in those early days were based on species that would now be considered “large” and were typically out-bred individuals. While this closely mirrors the clinical scenario, where genetic mismatches of donors and recipients can only be minimized in the selection process, these were not ideal models for studying the complexities and nuances of the immune system. Even when the rat was considered the standard model those early endeavors were limited by a small number of rat strains. The mouse model has provided us with an overwhelming array of strains, knockouts, knockins and transgenics that allow us to investigate the many layers of the innate and adaptive immune systems leading to a much greater understanding of immune responses. Fully vascularized heterotopic cardiac transplantation in the mouse has now been with us for four decades; the original papers describing this technique being published by Corry in 1973. In the subsequent 40 years, this technique has been used by many laboratories, including our own, and has become a powerful tool for the investigation of transplant immunity and ischemia reperfusion injury. Given the modern availability of mouse strains and mouse-related reagents, our current understanding of transplant immunity undoubtedly would not exist without such a technique.

Spontaneous allograft tolerance in B7-deficient mice independent of preexisting endogenous CD4+CD25+ regulatory T-cells.

Background. Acute cardiac allograft rejection requires host, but not donor, expression of B7-1/B7-2 costimulatory molecules. However, acute cardiac rejection requires direct antigen presentation by donor-derived antigen presenting cells to CD4 T-cells and does not require indirect antigen presentation to CD4 T-cells. Given this discrepancy in the literature and that the consequence of allograft exposure in B7-deficient mice is unknown; the goal of the study was to examine the antidonor status of allografted B7-1/B7-2-deficient hosts. Methods. C57Bl/6 B7-1/B7-2−/− mice were grafted with heterotopic BALB/c hearts. Recipients bearing long-term surviving allografts were used to examine the status of antidonor reactivity in vitro and in vivo. Tolerance was examined in vivo through adoptive transfer of splenocytes from graft-bearing animals to secondary immune-deficient Rag-1−/− hosts bearing donor-type or third-party cardiac allografts and by regulatory T-cell depletion with anti-CD25 antibody. Results. When transferred to B7-replete Rag-1−/− recipients, cells from naïve B7-1/B7-2−/− mice readily initiated cardiac allograft rejection. However, splenocytes transferred from long-term allograft acceptor B7-1/B7-2−/− hosts failed to reject donor-type hearts but acutely rejected third-party allografts. In addition, such cells did not reject (donor×third-party) F1 allografts. Finally, in vivo depletion of regulatory T-cells did not prevent long-term acceptance. Conclusions. Results demonstrate that B7-deficient T-cells are capable of acute cardiac allograft rejection in a B7-replete environment. Importantly, results also show that B7-deficient hosts do not simply ignore cardiac allografts, but rather spontaneously develop transferable, donor-specific tolerance and linked suppression in vivo. Interestingly, this tolerant state does not require endogenous CD4+CD25+ regulatory T-cells.

Revised Arterial Anastomosis for Improving Murine Kidney Transplant Outcomes

ABSTRACT Aim: One of the most challenging research microsurgical techniques is the mouse kidney transplant however, very few laboratories have made use of this important model due to its difficulty. One of the main obstacles to utilizing this procedure is the high incidence of post-operative arterial thrombosis. We believe this is caused by the path in which blood is required to flow from the recipient abdominal aorta, via the donor recipient aorta and on into the renal artery creating a tortuous route and areas of turbulence, which are prone to thrombus formation and failure of the graft. Methods: We describe revised methods of donor artery recovery, whereby the traditional transection of the donor aorta is replaced with a heel and toe cuff, which is created by dividing the donor abdominal aorta obliquely across the face of the renal arterial ostium, which then provides for an arterial end-to-side anastomosis of a scale similar to that used for the heterotopic heart model. This technique produces an anastomosis that facilitates free blood flow from the recipient abdominal aorta at less than 90° thereby reducing the likelihood of thrombus formation. Results: Utilizing this new technique the incidence of arterial thrombosis has decreased from 35% to 0% (n = 20 and 24, respectively) with no change in ischemia times. Conclusion: We describe a revised method of performing the arterial anastomosis during mouse kidney transplantation, which facilitates improved fluid dynamics by straightening the flow path for blood to the graft resulting in significantly reduced thrombus formation, excellent graft function, histology, and post-transplant survival.