A case of novel combined variations of the renal and testicular vessels.

Variations in the pattern of urogenital vessels can arise as a single occurrence or as a combination, which may increase the risk of unexpected injury during surgical procedures. Multiple variations in the renal and testicular vessels, in a novel combination, were observed during dissection of an 87-year-old Japanese male cadaver. In the present case, the patient had two renal arteries on each side. On the right side, the superior and inferior renal arteries emerged from the abdominal aorta at the L1 and L4 vertebrae levels, respectively. On the left side, the superior renal artery originated from the abdominal aorta at the level of the L1/L2 intervertebral disc, whereas the inferior renal artery arose at L4. The right testicular artery emerged from the abdominal aorta at the level of the L2 vertebra and crossed the inferior vena cava posteriorly. The venous system also exhibited some variations. The left renal vein passed posteriorly to the abdominal aorta and opened into the inferior vena cava at the level of the L2 vertebra. On the course to the inferior vena cava, the left renal vein was connected only to the first lumbar, azygos, and hemiazygos veins; blood was not collected from the left testicular and suprarenal veins, which usually open to the left renal vein. The patient had two right testicular veins. The lateral one opened into the angle between the right renal vein and the inferior vena cava at the level of the L2 vertebra, and the medial one drained into the inferior vena cava at a level slightly lower than the lateral one. Knowledge of the possible anatomical variations may be beneficial for performing safe retroperitoneal surgery and understanding the development of these vessels.

Quantitative analysis of the distribution of the myenteric plexus in the rabbit large intestine.

Rabbit large intestine has a segment-specific morphology and motility. However, the morphological features of the myenteric plexus, which controls intestinal motility, have not been characterized in each large intestinal segment. We investigated the myenteric plexus morphology in the rabbit large intestine using protein gene product 9.5 immunohistochemistry in whole-mount preparations. The tenial part of the first and second segments of the proximal colon had the most well developed myenteric plexus, while the caecum had the least. These findings suggest different neuronal control over the motility of each intestinal segment, thereby providing a fundamental understanding of the rabbit enteric nervous system.

Arterial branching pattern of the cranial mesenteric artery in the degu (Octodon degus).

BACKGROUND: The cranial mesenteric artery exhibits a species-specific ramification pattern that adapts to the morphology of the intestinal tract. The degu is a strictly herbivorous rodent with a well-developed large intestine with a spiral loop in the ascending colon; therefore, the cranial mesenteric artery likely demonstrates a degu-specific ramification pattern. Thus, we traced the cranial mesenteric artery to establish the detailed ramification pattern of the branches. METHODS: Eighteen male degus were injected with 0.3-0.8 ml of a latex mixture and water at a 1:1 ratio in conjunction with red acrylic paint coloring using a catheter inserted into the thoracic aorta. The cranial mesenteric artery was traced using a surgical microscope and photographed using a digital camera. RESULTS: The arteries emerging from the cranial mesenteric artery exhibited frequent variations in number, distribution area, anastomosis pattern, and branching order. In the most frequent cases (22%), the cranial mesenteric artery sequentially gave rise to caudal pancreaticoduodenal, middle colic, right colic, jejunal, and ileocolic arteries. The right and middle colic arteries exhibited four different ramification patterns. In the most common cases (67%), the middle and right colic arteries emerged independently from the cranial mesenteric artery. The former was distributed to the transverse and descending colon, whereas the latter sent branches to the spiral loop of the ascending colon. CONCLUSIONS: The complex ramification pattern of the right colic artery in the degu may be an adaptation to the characteristic running pattern of the ascending colon. Thus, we present the first comprehensive report of the arterial branching pattern of the cranial mesenteric artery in the degu.

Comparison of the retrosplenial cortex size between the degu (Octodon degus) and the Wistar rat (Rattus norvegicus).

The degu (Octodon degus) is a rodent that normally constructs burrows for nesting and rearing. To navigate inside these burrows, degus may use idiothetic and/or sensory cues more than visual information, which is less effective in burrows. Spatial information for navigation is processed in several key brain regions including the retrosplenial cortex (RS). However, the structural characteristics of the degu RS have not been previously reported. The present study measured the sizes of the RS and constituent areas 29 and 30 in the degu, and compared these to those found in the rat, which is a terrestrial rodent. The proportion of the rostrocaudal length of the entire RS relative to that of the entire cortex was significantly larger in degus versus rats. The proportion of the rostrocaudal length of the RS at levels rostral to the splenium of the corpus callosum relative to that of the entire cortex was also significantly larger in degus versus rats. Furthermore, the ratio of the estimated volume of area 29 relative to that of area 30 was significantly larger in degus versus rats. These results show that the degu has a rostrocaudally longer rostral RS with a larger area 29 compared to the rat, which suggests that these structural features may be relevant to differences in spatial information processing between the fossorial degu and terrestrial rat.

Branching patterns of the adrenal arteries in the degu (Octodon degus).

The degu has drawn increasing attention for use as an experimental animal in stress response studies due to its physiological features, such as diurnality and seasonal breeding, which differ from conventional laboratory rodents. Stress response is elicited by steroid hormones secreted by the adrenal gland, whose functions are controlled by pituitary hormones reaching through the adrenal arteries. However, knowledge of the arterial anatomy of the degu adrenal gland remains insufficient. To address this issue, we observed adrenal arteries in 20 male degus injected with red-colored latex. Adrenal arterial branching patterns were classified into Types 1-4, which respectively have 1 to 4 parent arteries that give rise to the adrenal arteries. Based on the combination of the parent arteries, Types 2 and 3 were categorized into subtypes a to c, while Type 4 was categorized into subtypes a and b. On the left side, Type 2 (45%) and Type 3 (45%) were predominant, whereas Type 1 (5%) and Type 4 (5%) were infrequent. On the right side, Type 2 (50%) and Type 3 (45%) were predominant, whereas Type 4 (5%) was infrequent. Type 1 was not present. There were 0 to 4 cranial, 1 to 4 middle and 1 to 4 caudal adrenal arteries, with the total number varying from 2 to 9. The present observation provides knowledge of comparative anatomical features of the degu adrenal arteries, which can serve as an anatomical basis for comparative endocrinological studies.

Arterial supply to the rat colon.

Rats are often used as animal models in studies such as on intestinal transplantation and anastomosis healing, which require colectomy. Although detailed information regarding arterial supply is important to establish accurate and reproducible experimental procedures, this has not been studied in the rat colon. Therefore, we analysed the detailed arterial distribution pattern and its individual variations in the colon of 34 rats. The rat colon received colic branches of the ileocolic artery, and the right, middle and left colic arteries. The single left colic artery constantly arose from the caudal mesenteric artery and was distributed to the descending colon, whereas the others showed variations in number and distribution. The ileocolic artery gave rise to one (12%) or two (88%) colic branches supplying the proximal ascending colon, and these branches formed rich, mesh-like anastomoses along the initial portion of the ascending colon. One (74%) or two (26%) right colic arteries originated from the cranial mesenteric artery and supplied the ascending colon and right colic flexure. Moreover, one (38%), two (56%) or three (6%) middle colic arteries emerged from the cranial mesenteric artery and were distributed to the transverse colon, left colic flexure and proximal descending colon. In total, we categorized the individual variations in arterial branching and anastomosis into 11 patterns. Arterial supply to the rat colon showed a specific pattern and frequent individual variations. These findings thus provide essential information for establishing reproducible models of rat colic surgery.

Arterial branching pattern of the rabbit femoral artery.

Rabbits have highly developed hindlimb muscles, whereas their bones are fragile, thus resulting in frequent hindlimb fractures. To repair these fractures, it is important to understand the arterial branching pattern of the femoral artery, as it provides the main blood supply to the hindlimb. Since the descriptions from prior studies are insufficient, the aim of the present study was to determine the detailed arterial branching pattern of the rabbit femoral artery. Therefore, to address this issue, we examined 30 male and 20 female New Zealand White rabbits after colored latex injections into the femoral artery. Results showed that the femoral artery gave rise to the pudendoepigastric trunk, along with the deep femoral, lateral circumflex femoral, superficial caudal epigastric, saphenous, descending genicular, and proximal and middle caudal femoral arteries, in conjunction with frequent individual variations. In all the observed halves, the last branch from the femoral artery was the distal caudal femoral artery. Individual variations in the branching pattern of these arteries occurred independently in the proximal and the distal portions of the femoral artery, and they were, respectively, categorized into four and three major types based on the number of the branching levels along the proximodistal axis of the femoral artery. The individual variations in the arterial branching pattern of the rabbit femoral artery that were demonstrated in the present study may provide an important anatomical basis for refining the orthopedic surgical procedure in the rabbit.

Arterial supply to the rabbit male genital organs.

The improvement of veterinary care has prolonged the lifespan of rabbits, and the number of rabbits suffering from age-related, male genital disorders may increase in the near future. This could result in increased opportunities for male genital surgery, requiring knowledge of their arterial anatomy, which, however, has not been sufficiently studied. Therefore, the arteries supplying the genitals were observed in 20 male New Zealand White rabbits. The testis was supplied by the testicular artery originating from the abdominal aorta. The right testicular artery usually emerged at a more cranial level than the left artery (65%). The testicular artery encircled the testis in the sagittal plane and bifurcated (95%) or trifurcated (5%) at the caudal extremity of the testis before entering the parenchyma. The epididymis was supplied by the epididymal branches, either from only the testicular artery (75% of the right and 80% of the left halves) or from both the testicular artery and aorta. The deferent duct was supplied in all halves by the dorsal and ventral branches of the deferential artery, which usually arose from the umbilical artery. The accessory genital glands were supplied by the dorsal branch of the deferential artery and the prostatic artery. The latter, which emerged from the internal iliac artery, exhibited 3 branching types. The most frequent type (55% of the right and 45% of the left halves) had 3 branches supplying the accessory genital glands. These findings will help improve rabbit genital surgery.

Ramification Pattern of the Arteries Supplying the Rabbit Female Genital Organs.

Uterine adenocarcinoma occurs in more than 60% of female rabbits aged 4 years and over. To cure or prevent this uterine disorder, ovariohysterectomy should be performed. Although knowledge of the arterial supply to the ovary, uterus, and vagina is required, few studies have described the arterial anatomy. Therefore, we dissected ovarian, uterine, and vaginal arteries in 15 New Zealand White and 15 Japanese White rabbits to clarify the anatomy. The ovarian artery arose from the abdominal aorta, and in 50% of cases, the left artery emerged more cranially than the right artery. The ovarian artery provided the ovarian, uterine, and tubal branches with three branching types. The most frequent type (67% of the halves on the right and 63% of the halves on the left) exhibited three branches that independently arose from the ovarian artery. The uterine artery usually originated from the umbilical artery, with its ramification pattern divided into two types, having one or two uterine arteries, respectively. The most frequent type (all halves on the right and 83% of the halves on the left) had one uterine artery that originated from the umbilical artery. We observed three types of vaginal artery origins, with the branching type where the vaginal artery arose from the internal iliac artery being the most frequent (97% of the halves on the right and 90% of the halves on the left). The detailed arterial supply pattern of the rabbit female genital organs determined in the present study will be helpful when performing rabbit gynecological surgeries. Anat Rec, 303:1478-1488, 2020. © 2019 American Association for Anatomy.

A case report of a rare ramification pattern and distribution area of the mesenteric arteries in a Japanese White rabbit (Oryctolagus cuniculus).

The rabbit intestinal tract is supplied by the cranial and caudal mesenteric arteries. Generally, the cranial mesenteric artery supplies the duodenum, jejunum, ileum, cecum, proximal colon and ascending and transverse distal colon, whereas the caudal mesenteric artery supplies the descending distal colon and rectum. The present study describes an abnormal branching pattern of the cranial and caudal mesenteric arteries in a Japanese White rabbit, where the caudal mesenteric artery but not the cranial mesenteric artery supplied the distal ileum, cecum, proximal colon and ascending and transverse distal colon. Such a rare mesenteric arterial ramification pattern may be explained by anomalies of the remaining anastomotic branches between the primitive mesenteric arteries and regressed their parent arteries during the developmental process.

Wall thickness and mucous cell distribution in the rabbit large intestine.

To achieve a better understanding of rabbit large intestinal functions, such as production of hard and soft feces and cecal fermentation, knowledge of the intestinal wall structure is essential. However, such knowledge is far from complete. Therefore, the aims of this study were to measure the thickness of the wall and its constituent layers and describe distribution of mucous cells in each segment of the large intestine in New Zealand White rabbits. Results showed that the cecum had the thinnest entire wall throughout the large intestine, and the fusus coli and rectum had a thicker entire wall in comparison to the cecum, the first segment of the proximal colon, the second segment of the proximal colon, and the distal colon. Moreover, the thickness of the mucosa in the fusus coli and that of the inner and outer layers of the tunica muscularis in the rectum were greater than that of the other segments. Mucous cells in the mucosa were the fewest in the cecum and most numerous in the fusus coli. This study provides detailed knowledge of the wall thickness and distribution of mucous cells in the large intestine of the rabbit. These findings are important for improving our understanding of rabbit intestinal physiology and pathology.

Anatomical variations of the arterial branches from the rat iliac arteries.

Animal disease models contribute to a better understanding of the pathogenic mechanisms of human and animal diseases and help develop treatments for them. Ligation of the rat iliac arteries is performed to reproduce erectile dysfunction and peripheral arterial disease. Although knowledge of the ramification of branches from the rat iliac artery is important to perform such surgery, descriptions in previous studies are insufficient. Therefore, 17 male and 18 female Wistar rats were observed to elucidate the detailed ramification patterns of branches from the iliac arteries with the latex injection method. The iliac arteries branched off the umbilical, cranial gluteal, lateral and medial circumflex femoral, external pudendal, and caudal epigastric arteries, and the common trunk of the caudal gluteal and internal pudendal arteries. The branching pattern of the umbilical, cranial and caudal gluteal, and internal pudendal arteries varied greatly and was categorized as Types 1 to 3 based on the number of branching levels along the proximodistal axis of the iliac arteries. Based on the same criteria, the ramification patterns of the lateral and medial circumflex femoral arteries were also divided into Groups 1 and 2. The external pudendal and caudal epigastric arteries originated from the external iliac artery mainly as a common trunk or less frequently as independent arteries in this order. The detailed branching patterns of the rat iliac arteries elucidated in the present study are beneficial for the refinement of surgical procedures.

Arterial supply to the rabbit adrenal gland.

The adrenal gland regulates stress responses by releasing steroid hormones, whose synthesis and secretion are influenced by adrenal blood flow. Adrenalectomy is commonly performed in rabbits to study the function of the adrenal gland. Although knowledge of the arterial supply to the adrenal gland forms the anatomical basis of the surgery, its description in prior studies is incomplete for the rabbit. Therefore, we observed the adrenal arteries in 27 male and 11 female New Zealand White rabbits using the colored latex injection method. The branching pattern of the adrenal arteries was divided into three major types based on the number of parent arteries that gave rise to the adrenal arteries. Thirty-four percent of right halves exhibited one parent artery and were categorized as type 1. Fifty-five percent of right halves and 76% of left halves had two parent arteries and were categorized as type 2. Eleven percent of right halves and 24% of left halves had three parent arteries and were categorized as type 3. The number of adrenal arteries varied from 3 to 16 on the right, 3 to 18 on the left, and 9 to 30 in total in each individual. These findings demonstrate the remarkable individual variation in arterial supply to the rabbit adrenal gland, suggesting that such variations should always be considered during experimental treatments in the rabbit.

Macroscopic anatomical study of the distribution of the cranial mesenteric artery to the intestine in the rabbit.

Intestinal surgery is commonly performed to cure bowel obstruction in rabbits, but detailed descriptions of the arterial supply to the intestine are incomplete. We investigated anatomical variations of the distribution of the cranial mesenteric artery to the intestine in 33 New Zealand White rabbits by injecting colored latex into the arteries. The cranial mesenteric artery arose independently from the abdominal aorta at about 2.0 cm caudal to the celiac artery and branched off the pancreaticoduodenal, middle colic, ileocecocolic, jejunal and ileal arteries. One or occasionally two caudal pancreaticoduodenal arteries supplied the distal duodenum, and one to three middle colic arteries supplied the transverse colon and the initial portion of the descending colon. The ileocecocolic artery arose distal to the middle colic arteries and provided the right colic, ileocecal and appendicular arteries, and branches to the proximal colon, with various branching patterns, which were grouped into four major types. These arteries and branches supplied the ileum, cecum, appendix and proximal colon. The cranial mesenteric artery also provided the jejunal arteries (predominantly 17; range 11-21) and one ileal artery supplying the jejunum and proximal ileum, respectively. The results show that the distribution patterns of the cranial mesenteric artery to the intestine in the rabbit are highly specialized to this species. Such specialization should always be considered when performing intestinal surgery in rabbits.

Anatomical variations of the arterial supply to the adrenal gland in the rat.

The adrenal gland is an essential endocrine organ for the stress response. The functions of this organ may be studied by ligation of the adrenal artery or adrenalectomy. However, in prior studies, descriptions of the anatomical variations of the adrenal artery were insufficient and inconsistent. Therefore, anatomical variations of the arterial supply to the adrenal gland were studied in 18 male and 18 female Wistar rats by colored latex injection into the arteries. The vascularization pattern was categorized into 4 types based on the origin of each adrenal artery. The cranial and middle adrenal arteries arose from the caudal phrenic artery in Types 1-3, but the caudal adrenal artery emerged from the caudal phrenic artery in Type 1, from the renal artery in Type 2 and from the abdominal aorta in Type 3. In Type 4, the cranial and middle adrenal arteries stemmed from the cranial phrenic artery, and the caudal adrenal artery arose from the caudal phrenic artery. The number of adrenal arteries varied from 3 to 11 on the left side and from 4 to 12 on the right side, and the total varied from 9 to 20 (predominantly 14) in each individual. There was no sex difference in the vascularization pattern. The results show that more individual variations occur in the adrenal arteries of rats than was previously reported. Such variations should always be considered when experimental treatments of the rat adrenal gland are performed.