Constant innervation despite pubertal growth of the mouse penis

Acute intranasal oxytocin dose enhances social preference for parents over peers in male but not female peri-adolescent California mice (Peromyscus californicus)

Peri-adolescence is a critical developmental stage marked by profound changes in the valence of social interactions with parents and peers. We hypothesized that the oxytocin (OXT) and vasopressin (AVP) systems, known for influencing social behavior, would be involved in the maintenance and breaking of bonding behavior expressed by very early peri-adolescent males and females. In rodents, OXT is associated with mother-pup bonding and may promote social attachment to members of the natal territory. AVP, on the other hand, can act in contrasting ways to OXT and has been associated with aggression and territoriality. Specifically, we predicted that in peri-adolescent male and female juveniles of the biparental and territorial California mouse (Peromyscus californicus), a) OXT would increase the social preferences for the parents over unfamiliar age-matched peers (one male and one female), and b) AVP would break the parent-offspring bond and either increase time in the neutral chamber and/or approach to their unfamiliar and novel peers. We examined anxiety and exploratory behavior using an elevated plus maze and a novel object task as a control. Peri-adolescent mice were administered an acute intranasal (IN) treatment of 0.5 IU/kg IN AVP, 0.5 IU/kg IN OXT, or saline control; five minutes later, the behavioral tests were conducted. As predicted, we found that IN OXT enhanced social preference for parents; however, this was only in male and not female peri-adolescent mice. IN AVP did not influence social preference in either sex. These effects appear specific to social behavior and not anxiety, as neither IN OXT nor AVP influenced behavior during the elevated plus maze or novel object tasks. To our knowledge, this is the first evidence indicating that OXT may play a role in promoting peri-adolescent social preferences for parents and delaying weaning in males.

Elephant facial motor control

We studied facial motor control in elephants, animals with muscular dexterous trunks. Facial nucleus neurons (~54,000 in Asian elephants, ~63,000 in African elephants) outnumbered those of other land-living mammals. The large-eared African elephants had more medial facial subnucleus neurons than Asian elephants, reflecting a numerically more extensive ear-motor control. Elephant dorsal and lateral facial subnuclei were unusual in elongation, neuron numerosity, and a proximal-to-distal neuron size increase. We suggest that this subnucleus organization is related to trunk representation, with the huge distal neurons innervating the trunk tip with long axons. African elephants pinch objects with two trunk tip fingers, whereas Asian elephants grasp/wrap objects with larger parts of their trunk. Finger "motor foveae" and a positional bias of neurons toward the trunk tip representation in African elephant facial nuclei reflect their motor strategy. Thus, elephant brains reveal neural adaptations to facial morphology, body size, and dexterity.

Restoring Impaired Fertility Through Diet: Observations of Switching From High-Fat Diet During Puberty to Normal Diet in Adulthood Among Obese Male Mice

BACKGROUND

Obesity is associated with a decrease in testicular function, yet the effects and mechanisms relative to different stages of sexual development remain unclear. The aim of this study is to determine whether high-fat diet-induced obesity impairs male fertility during puberty and in adulthood, and to ascertain its underlying mechanisms. This study aims to further reveal whether restoring to a normal diet can improve impaired fertility.

METHODS

Male mice were divided into 6 groups: the group N and H exposed to a normal diet or high-fat diet during puberty. The group NN or NH were further maintained a normal diet or exposed to high-fat diet in adulthood, the group HH or HN were further maintained high-fat diet or switched to normal diet in adulthood. Metabolic parameters, fertility parameters, testicular function parameters, TUNEL staining and testicular function-related proteins were evaluated, respectively.

RESULTS

The fertility of the mice in the high-fat diet group was impaired, which validated by declines in pregnancy rates and litter weight loss. Further analysis demonstrated the increased level of oxidative stress, the increased number of spermatogenic cell apoptosis and decreased number of sperm and decreased acrosome integrity. The expression of steroidogenic acute regulatory (StAR) and spermatogenesis related proteins (WT-1) decreased. Fertility among the HN group recovered, accompanied by the recovery of metabolism, fertility and testicular function parameters, StAR and WT-1 expression.

CONCLUSIONS

The findings suggest that high-fat diet-induced obesity impairs male fertility during puberty and in adulthood. The loss of acrosome integrity, the increase of oxidative stress, the increase of cells apoptosis and the down-regulation of StAR and WT-1 may be the underlying mechanisms. Switching from high-fat diets during puberty to normal diets in adulthood can improve male fertility.

An isomorphic three-dimensional cortical model of the pig rostrum

Physiological studies of the last century mapped a somatosensory cortical gyrus representing the pig's rostrum. Here, we describe the extraordinary correspondence of this gyrus to the rostrum. The pig rostrum is packed with microvibrissae (~470 per hemi-rostrum) and innervated by a prominent infraorbital nerve, containing about 80,000 axons. The pig's rostrum has three major skin-folds. The nostrils have a rectangular medial wall and a funnel-like lateral opening, nasal channels run obliquely from lateral (surface) to medial (inside). The rostrum gyrus mimics rostrum geometry in great detail. The putative representation of skin folds coincides with blood sinus and folds of the rostrum gyrus. The putative nostril representation is an oblique sulcus running from lateral (surface) to medial (inside). As observed in rodents, Layer 4 is thin in the nostril sulcus. The side of the nostril sulcus representing the medial wall of the nostril is rectangular, whereas the side of the nostril sulcus representing the lateral wall is funnel-like. Proportions and geometry of the rostrum and the rostrum gyrus are similar, albeit with a collapsed nostril and a larger interindividual variability in the gyrus. The pig's cortical rostrum gyrus receives dense thalamic innervation, has a thin Layer 1 and contains roughly 8 million neurons. With all that, the rostrum gyrus looks like a model of the pig rostrum at a scale of ~1:2. Our findings are reminiscent of the raccoon cortex with its forepaw-like somatosensory forepaw-representation. Representing highly relevant afferents in three-dimensional body-part-models might facilitate isomorphic cortical computations in large-brained tactile specialists.

Anatomy of the mouse penis and internal prepuce

This paper addresses a confusing issue of preputial anatomy of the mouse. The term "internal prepuce" was used in 2013 to describe a preputial structure integral to the mouse glans penis. Subsequently in 2015 the same term was applied by another group to describe entirely different morphology, generating confusion in the literature. Because it is inappropriate to use the same term to describe entirely different structures, we take this opportunity to provide further descriptive information on the internal prepuce of the mouse employing gross dissection, analysis of serial histologic section sets, three-dimensional reconstruction, scanning electron microscopy and immunohistochemistry. For this purpose, we review and illustrate the relevant literature and provide some additional new data using standard morphological techniques including immunohistochemistry. The mouse internal prepuce is integral to the glans penis and clearly is involved in sexual function in so far as it contains a major erectile body innervated by penile nerves. The development of the mouse internal prepuce is described for the first time and related to the development of the corpus cavernosum glandis.