René Zempoalteca

An anatomical and electrophysiological study of the genitofemoral nerve and some of its targets in the male rat.

Anatomical descriptions of the genitofemoral nerve (GFn) innervating the lower pelvic area are contradictory. Here we re‐examine its origin and innervation by its various branches of principal target organs in the male rat. Using gross dissection, electrophysiological techniques and retrograde tracing of motoneurones with horseradish peroxidase, we confirm that the GFn originates from lumbar spinal nerves 1 and 2, and that at the level of the common iliac artery it divides into a lateral femoral and a medial genital branch. In contrast to previous studies, we report that the genital and not the femoral branch innervates the abdominal–inguinal skin, and not only the genital but also the femoral branch innervates the cremaster muscle (Cm) surrounding the testes. Motoneurones innervating the Cm proper are located in the ventral nucleus of L1 and L2, and those innervating the muscular transition region of the rostral Cm are located in the ventral nucleus in L1 and the ventrolateral nucleus in L2. The GFn may contribute to male reproductive performance by transmitting cutaneous information during copulation and, via contraction of the Cm to promote ejaculation, the protective displacement of the testes into the abdominal cavity during fighting and as a sperm‐protecting thermoregulatory measure.

Pattern of sensory innervation of the perineal skin in the female rat.

Here we describe the nerves innervating the perineal skin together with their sensory fields in the adult female rat. Electrophysiological recording showed that the lumbosacral and L6-S1 trunks, in part by way of the sacral plexus, transmit sensory information from the perineal skin via four nerves: the viscerocutaneous branch of the pelvic nerve innervating the skin at the midline between the vaginal opening and anus, the sensory branch of the pudendal nerve innervating the clitoral sheath, the distal perineal branch of the pudendal nerve innervating a broad area of skin adjacent to the vaginal opening and anus, and the proximal perineal branch of the sacral plexus innervating a broad area of skin adjacent to the clitoris and vaginal opening. The sensory fields of three of these nerves overlapped to some degree: the viscerocutaneous branch of the pelvic and the distal perineal branch of the pudendal nerves at the midline skin between the vaginal opening and the anus, and the distal perineal branch of the pudendal nerve and the proximal perineal branch of the sacral plexus at the skin lateral to the vaginal opening. Such overlap might provide a safeguard helping to ensure that somatosensory input from the perineal region important for triggering reproductive and nonreproductive reflexes reaches the CNS.

Sensory and somatomotor components of the “sensory branch” of the pudendal nerve in the male rat

Surgical microscopy and electrophysiological techniques were used to describe in the adult male rat the peripheral distribution of the sensory branch of the pudendal nerve (SBPdn) and its sensory and somatomotor axonal components. Gross and histological features of the urethralis muscle were also determined. We propose to name the SBPdn branches according to the corresponding target structure. We found branches to the urethral diverticulum, major pelvic ganglion, corpus cavernosus of the penis, urethralis muscle, preputial glands, corpus spongiosus of the penis, foreskin and glans penis. Under the pubic bone three anastomotic branches form a bridge-like structure we called pelvic plexus. Through electrophysiological studies it was determined that the SBPdn carries efferent fibers to the striated urethralis muscle, as well as afferent axons from the glans penis and foreskin. We concluded that the SBPdn of the male rat has sensory and somatomotor components. This nerve is mixed and not exclusively sensory as was previously described. The finding of the anatomic relation to the major pelvic ganglion implies nerve communication with the autonomic nervous system. The functions of the somatomotor component and nerves to the urethral diverticulum, cavernosus bodies and preputial glands of the SBPdn remain to be determined. According to its targets, this innervation could contribute in the control of genitourinary functions such as voiding, erection, ejaculation and urinary marking.

The role of pelvic and perineal striated muscles in urethral function during micturition in female rabbits

To evaluate the role of pelvic and perineal striated muscles on urethral function during micturition.

Anatomical organization and somatic axonal components of the lumbosacral nerves in female rabbits.

To determine the anatomical organization and somatic axonal components of the lumbosacral nerves in female rabbits.

Activity of the external urethral sphincter evoked by genital stimulation in male rats

To determine whether the external urethral sphincter (EUS) fasciculi of male rats respond to the mechanical stimulation of genital structures and to characterize the pattern of the electromyographic (EMG) activity of the three regions of the EUS: the cranial (CrEUS), the medial (MeEUS) and the caudal (CaEUS).

Anatomic and functional properties of bulboglandularis striated muscle support its contribution as sphincter in female rabbit micturition

To determine anatomic and functional properties of the bulboglandularis muscle (Bgm) for clarifying its role in micturition in female rabbits.

Multiparity modifies contractile properties of pelvic muscles affecting the genesis of vaginal pressure in rabbits

To characterize the contractile properties of the bulbospongiosus (Bsm), isquiocavernosus (Ism), and pubococcygeus muscles (Pcm), and their involvement in the genesis of vaginal pressure in nulliparous and multiparous rabbits.

The Role of Pelvic and Perineal Muscles in Reproductive and Excretory Functions

Excretory and reproductive functions are underlaid by autonomicand somatic-neural control that regulates the pelvic and the perineal structures in mammals. Viscera and striated and smooth muscles are involved in complex and multiple reflexes occurring in the pelvic cavity (Komisaruk and Sansone, 2003; Pacheco et al., 1989; Thor and de Groat, 2010). In women, this region must accommodate the growing fetus during pregnancy and the passage of the newborn during childbirth (Ashton-Miller & DeLancey, 2007). For this to occur, the fetal head has to undergo a series of internal translations and rotations, aided by the maternal effort in the form of active pushing and uterine contraction (Li et al., 2010). Functions, such as urination and defecation, are also regulated by the different autonomic and somatic reflexes of the pelvic cavity. During pregnancy and parturition, the fetal weight, translations, and rotations on pelvic structures, such as pelvic and perineal floor muscles, cause injury to the components of the pelvic reflexes (Kearney, 2006; Lanzarone & Dietz, 2008). This has been associated with visceral disorders, such as pelvic-organ prolapse and urinary and fecal incontinence (Ashton-Miller & DeLancey, 2007; Smith et al., 1989). One of the techniques frequently used to evaluate the participation of pelvic and perineal muscles during normal and pathological functions is electromyography. The electromyographic (EMG) recordings are extremely useful to evaluate the participation of pelvic and perineal muscles during the normal and pathological functions of this female anatomy. The goal of our chapter is to review the literature of the activity of pelvic and perineal muscles and the several viscerosomatic reflexes involved in sexual response and urination in female mammals. Measurements of the pelvicand perineal-muscle EMGs in laboratory rabbits, focusing on methods and results, and the alterations of their activity associated with dysfunctions, particularly with urinary incontinence, will be also reviewed.

Early postnatal development of electrophysiological and histological properties of sensory sural nerves in male rats that were maternally deprived and artificially reared: Role of tactile stimulation: Maternal Deprivation and Development of PNS

Early adverse experiences disrupt brain development and behavior, but little is known about how such experiences impact on the development of the peripheral nervous system. Recently, we found alterations in the electrophysiological and histological characteristics of the sensory sural (SU) nerve in maternally deprived, artificially reared (AR) adult male rats, as compared with maternally reared (MR) control rats. In the present study, our aim was to characterize the ontogeny of these alterations. Thus, male pups of four postnatal days (PND) were (1) AR group, (2) AR and received daily tactile stimulation to the body and anogenital region (AR‐Tactile group); or (3) reared by their mother (MR group). At PND 7, 14, or 21, electrophysiological properties and histological characteristics of the SU nerves were assessed. At PND 7, the electrophysiological properties and most histological parameters of the SU nerve did not differ among MR, AR, and AR‐Tactile groups. By contrast, at PND 14 and/or 21, the SU nerve of AR rats showed a lower CAP amplitude and area, and a significant reduction in myelin area and myelin thickness, which were accompanied by a reduction in axon area (day 21 only) compared to the nerves of MR rats. Tactile stimulation (AR‐Tactile group) partially prevented most of these alterations. These results suggest that sensory cues from the mother and/or littermates during the first 7–14 PND are relevant for the proper development and function of the adult SU nerve.